drm/amd/pm: update driver if file for sienna cichlid

Update driver if file for sienna cichlid.

Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Reviewed-by: Jiansong Chen <Jiansong.Chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>