drm/amd/powerplay: enable Graphics Clock Deep Sleep for sienna_cichlid

Enable Graphics Clock Deep Sleep 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

@@ -269,7 +269,8 @@ sienna_cichlid_get_allowed_feature_mask(struct smu_context *smu,
 	memset(feature_mask, 0, sizeof(uint32_t) * num);
 
 	*(uint64_t *)feature_mask |= FEATURE_MASK(FEATURE_DPM_PREFETCHER_BIT)
-				| FEATURE_MASK(FEATURE_DPM_FCLK_BIT);
+				| FEATURE_MASK(FEATURE_DPM_FCLK_BIT)
+				| FEATURE_MASK(FEATURE_DS_GFXCLK_BIT);
 
 	if (adev->pm.pp_feature & PP_SCLK_DPM_MASK)
 		*(uint64_t *)feature_mask |= FEATURE_MASK(FEATURE_DPM_GFXCLK_BIT);