CVE-2026-63856 drm/amdgpu/vcn: set no_user_fence for VCN v2.0 enc/dec rings

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/vcn: set nouserfence for VCN v2.0 enc/dec rings VCN encoder and decoder rings do not support 64-bit user fence writes, reject CS submissions with user fences. cherry picked from commit...