drm/amd/powerplay: enable df cstate control on swSMU routine

Currently this is only supported on Vega20 with 40.50 and later
SMC firmware.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
4 files changed