drm/amd/powerplay: move the function of is_dpm_running to asic file

the function os is_dpm_running is aisc related function,
so move them to asic file.

Signed-off-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>