perf: RISCV: Fix panic on pmu overflow handler

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "drivers/perf/riscv_pmu_sbi.c"
                    ],
                    "versions": [
                        {
                            "version": "4905ec2fb7e6421c14c9fb7276f5aa92f60f2b98",
                            "lessThan": "3ede8e94de6b834b48b0643385e66363e7a04be9",
                            "status": "affected",
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                        {
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                            "status": "affected",
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                    ]
                }

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "drivers/perf/riscv_pmu_sbi.c"
                    ],
                    "versions": [
                        {
                            "version": "5.18",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "5.18",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.23",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.7.11",
                            "lessThanOrEqual": "6.7.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.8",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }