drm/amd/pm: enable DCS

Enable DCS

V1: Enable Async DCS.
V2: Add the ppfeaturemask bit to enable from the modprobe parameter.
V3:
1. add the flag to skip APU support.
2. remove the hunk for workload selection since
it doesn't impact the function.

Signed-off-by: Kenneth Feng <kenneth.feng@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>