drm/amdgpu: add VPE 6.1.0 support

Add skeleton driver code. (Ray)
Add initial support for Video Processing Engine. (Lang)

Signed-off-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Lang Yu <Lang.Yu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>