afs: Fix missing kunmap in afs_dir_search_bucket()

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "fs/afs/dir_search.c"
                    ],
                    "versions": [
                        {
                            "version": "a5b5beebcf96d5e8a2fc79856c2ac1e93f82478e",
                            "lessThan": "c5fa4eb9c4b2c744ba88fb4ff2d729a158e66832",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "a5b5beebcf96d5e8a2fc79856c2ac1e93f82478e",
                            "lessThan": "f57d4728ac54921b871868c5d5bd29b8ab50ee12",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "a5b5beebcf96d5e8a2fc79856c2ac1e93f82478e",
                            "lessThan": "950ae84b5cc944fbe27d81806d0b76af765f779c",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                }

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "fs/afs/dir_search.c"
                    ],
                    "versions": [
                        {
                            "version": "6.14",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.14",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.53",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.7",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }