drm/amdgpu/vcn: custom video info caps for sriov

for sriov, we added a new flag to indicate av1 support,
this will override the original caps info.

Signed-off-by: Jane Jian <Jane.Jian@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>