drm/amdgpu/vcn: Add sriov VCN v4_0 unified queue support

Enable unified queue support for sriov, abandon all previous
multi-queue settings

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jane Jian <Jane.Jian@amd.com>
Reviewed-by: Ruijing Dong <ruijing.dong@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>