net/sched: sch_qfq: do not free existing class in qfq_change_class()

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/sched/sch_qfq.c"
                    ],
                    "versions": [
                        {
                            "version": "462dbc9101acd38e92eda93c0726857517a24bbd",
                            "lessThan": "2a64fb9b47afffeb5dbab5fd3a518e1436dcc90e",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "462dbc9101acd38e92eda93c0726857517a24bbd",
                            "lessThan": "cff6cd703f41d8071995956142729e4bba160363",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "462dbc9101acd38e92eda93c0726857517a24bbd",
                            "lessThan": "f06f7635499bc806cbe2bbc8805c7cef8b1edddf",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "462dbc9101acd38e92eda93c0726857517a24bbd",
                            "lessThan": "0a234660dc70ce45d771cbc76b20d925b73ec160",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "462dbc9101acd38e92eda93c0726857517a24bbd",
                            "lessThan": "362e269bb03f7076ba9990e518aeddb898232e50",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "462dbc9101acd38e92eda93c0726857517a24bbd",
                            "lessThan": "e9d8f11652fa08c647bf7bba7dd8163241a332cd",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "462dbc9101acd38e92eda93c0726857517a24bbd",
                            "lessThan": "3879cffd9d07aa0377c4b8835c4f64b4fb24ac78",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                }

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/sched/sch_qfq.c"
                    ],
                    "versions": [
                        {
                            "version": "3.8",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "3.8",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.10.249",
                            "lessThanOrEqual": "5.10.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.15.199",
                            "lessThanOrEqual": "5.15.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.1.162",
                            "lessThanOrEqual": "6.1.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.122",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.67",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.7",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.19",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }