iommu/vt-d: Fix oops due to out of scope access

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "drivers/iommu/intel/iommu.c"
                    ],
                    "versions": [
                        {
                            "version": "7d0c9da6c1509664d96488042bacc02308ca33b2",
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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/iommu/intel/iommu.c"
                    ],
                    "versions": [
                        {
                            "version": "6.6",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.6",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.33",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.0.10",
                            "lessThanOrEqual": "7.0.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.1",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }