drm/amd/powerplay: add arcturus_is_dpm_running function for arcturus

add arcturus_is_dpm_running function

Signed-off-by: Chengming Gui <Jack.Gui@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>