drm/amdgpu: enable SDMA power gating for rn

Enable SDMA PG flag during device ip early init.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Prike Liang <Prike.Liang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1174,7 +1174,7 @@ static int soc15_common_early_init(void *handle)
 				 AMD_CG_SUPPORT_ATHUB_LS |
 				 AMD_CG_SUPPORT_ATHUB_MGCG |
 				 AMD_CG_SUPPORT_DF_MGCG;
-		adev->pg_flags = 0;
+		adev->pg_flags = AMD_PG_SUPPORT_SDMA;
 		adev->external_rev_id = adev->rev_id + 0x91;
 
 		if (adev->pm.pp_feature & PP_GFXOFF_MASK)