display: Cleanup Edges when display is closed

This could happen if closing the display when dragging a window, unlikely, but
better to use the cleanup function since we have it.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/581

src/core/display.c

@@ -725,7 +725,7 @@ meta_display_open (void)
   display->grab_tile_mode = META_TILE_NONE;
   display->grab_tile_monitor_number = -1;
 
-  display->grab_edge_resistance_data = NULL;
+  meta_display_cleanup_edges (display);
 
   meta_display_init_keys (display);