drm/amdgpu/vangogh: don't check for dpm in is_dpm_running when in suspend

Do the same thing we do for Renoir.  We can check, but since
the sbios has started DPM, it will always return true which
causes the driver to skip some of the SMU init when it shouldn't.

Reviewed-by: Zhan Liu <zhan.liu@amd.com>
Acked-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org