drm/amdgpu:Add DPG mode support for vcn 1.0

Add DPG mode start/stop/mc_resume/clock_gating to
support vcn 1.0 DPG mode.

Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>