drm/amdgpu/vcn: add unified queue ib test

- add unified queue headers
- add unified queue ib tests

Acked-by: Leo Liu <leo.liu@amd.com>
Signed-off-by: Ruijing Dong <ruijing.dong@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>