drm/amdgpu/nv: don't expose AV1 if VCN0 is harvested

Only VCN0 supports AV1.

Reviewed-by: Leo Liu <leo.liu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>