add enable_umd_pstate to support sys interface for SMU11.
Signed-off-by: Chengming Gui <Jack.Gui@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>