drm/amd/powerplay: add new interface for vcn powergating

add new interface for vcn powrergating and vcn dpm as well.

Signed-off-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Jack Xiao <Jack.Xiao@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>