drm/amdgpu: enable sdma clock gating for Arcturus

Init sdma MGCG/LS flag

Signed-off-by: Le Ma <[e-mail]>
Reviewed-by: Feifei Xu <[e-mail]>
Reviewed-by: Kenneth Feng <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 			AMD_CG_SUPPORT_GFX_CGCG |
 			AMD_CG_SUPPORT_GFX_CGLS |
 			AMD_CG_SUPPORT_HDP_MGCG |
-			AMD_CG_SUPPORT_HDP_LS;
+			AMD_CG_SUPPORT_HDP_LS |
+			AMD_CG_SUPPORT_SDMA_MGCG |
+			AMD_CG_SUPPORT_SDMA_LS;
 		adev->pg_flags = 0;
 		adev->external_rev_id = adev->rev_id + 0x32;
 		break;