CVE-2026-68102 drm/amdgpu: fix aperture mapping leak

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: fix aperture mapping leak amdgpupciremove calls drmdevunplug before invoking the driver fini routines. This causes drmdeventer in amdgputtmfini to always return false, so iounmapaperbasekaddr never runs on normal driv...