drm/amd/powerplay: enable Ultra Low Voltage for sienna_cichlid

Support Ultra Low Voltage for sienna_cichlid.
Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/sienna_cichlid_ppt.c

@@ -277,6 +277,9 @@ sienna_cichlid_get_allowed_feature_mask(struct smu_context *smu,
 	if (adev->pm.pp_feature & PP_SOCCLK_DPM_MASK)
 		*(uint64_t *)feature_mask |= FEATURE_MASK(FEATURE_DPM_SOCCLK_BIT);
 
+	if (adev->pm.pp_feature & PP_ULV_MASK)
+		*(uint64_t *)feature_mask |= FEATURE_MASK(FEATURE_GFX_ULV_BIT);
+
 	return 0;
 }