drm/amdgpu: fix tonga smu resume

Need to make sure smu buffers are pinned on resume.  This
matches what Fiji does.

Cc: stable@vger.kernel.org
Reviewed-by: Junwei Zhang <Jerry.Zhang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Ken Wang <Qingqing.Wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -122,25 +122,12 @@ static int tonga_dpm_hw_fini(void *handle)
 
 static int tonga_dpm_suspend(void *handle)
 {
-	return 0;
+	return tonga_dpm_hw_fini(handle);
 }
 
 static int tonga_dpm_resume(void *handle)
 {
-	int ret;
-	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
-
-	mutex_lock(&adev->pm.mutex);
-
-	ret = tonga_smu_start(adev);
-	if (ret) {
-		DRM_ERROR("SMU start failed\n");
-		goto fail;
-	}
-
-fail:
-	mutex_unlock(&adev->pm.mutex);
-	return ret;
+	return tonga_dpm_hw_init(handle);
 }
 
 static int tonga_dpm_set_clockgating_state(void *handle,