drm/radeon: use locked rmmap to remove sarea mapping.

this exports the locked version of the symbol as struct_mutex locks it all.
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_bufs.c

@@ -440,6 +440,7 @@ int drm_rmmap_locked(struct drm_device *dev, drm_local_map_t *map)
 
 	return 0;
 }
+EXPORT_SYMBOL(drm_rmmap_locked);
 
 int drm_rmmap(struct drm_device *dev, drm_local_map_t *map)
 {

drivers/gpu/drm/radeon/radeon_cp.c

@@ -1804,7 +1804,7 @@ void radeon_master_destroy(struct drm_device *dev, struct drm_master *master)
 
 	master_priv->sarea_priv = NULL;
 	if (master_priv->sarea)
-		drm_rmmap(dev, master_priv->sarea);
+		drm_rmmap_locked(dev, master_priv->sarea);
 
 	drm_free(master_priv, sizeof(*master_priv), DRM_MEM_DRIVER);