drm/powerplay : send SMC message to set XGMI pstate

Send message with parameter to SMC to set xgmi pstate

Signed-off-by: shaoyunl <shaoyun.liu@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>