drm/amd/powerplay: enable ac/dc feature on navi10

enable ac/dc feature on navi10. currently we don't have
the case to verify it.

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