drm/amdgpu: enable mmhub clock gating for Arcturus

Init MC_MGCG/LS flag. Also apply to athub CG.
Signed-off-by: Le Ma <le.ma@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/mmhub_v9_4.c

@@ -615,7 +615,6 @@ int mmhub_v9_4_set_clockgating(struct amdgpu_device *adev,
 	return 0;
 }
 
-/* TODO: get 2 mmhub instances CG state */
 void mmhub_v9_4_get_clockgating(struct amdgpu_device *adev, u32 *flags)
 {
 	int data, data1;

drivers/gpu/drm/amd/amdgpu/soc15.c

@@ -1127,7 +1127,9 @@ static int soc15_common_early_init(void *handle)
 			AMD_CG_SUPPORT_HDP_MGCG |
 			AMD_CG_SUPPORT_HDP_LS |
 			AMD_CG_SUPPORT_SDMA_MGCG |
-			AMD_CG_SUPPORT_SDMA_LS;
+			AMD_CG_SUPPORT_SDMA_LS |
+			AMD_CG_SUPPORT_MC_MGCG |
+			AMD_CG_SUPPORT_MC_LS;
 		adev->pg_flags = 0;
 		adev->external_rev_id = adev->rev_id + 0x32;
 		break;