drm/amd/pm: Add interface for request WGPs

When user specifies a reduced WGP(CU) config via disalbe_cu module
parameter, this does not disable the clocks which uses additional
power. This interface send active WGP number to SMU and SMU will
cooperate with RLC to power off relative WGPs.

v2: Add request active WGPs in Vangogh smu post init.

Signed-off-by: Jinzhou.Su <Jinzhou.Su@amd.com>
Reviewed-by: Jiansong Chen <Jiansong.Chen@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>