wps: update SBS before leaving WPS

The backdrop layer for the WPS was redrawn
before returning to the SBS, resulting in
unsightly visual effects such as album art
(drawn on the backdrop) losing a frame that
was drawn in the foreground.

Change-Id: If5bb1ba83d79d6d1f637e06f9cc5eab3b97d5906

apps/gui/wps.c

@@ -546,6 +546,7 @@ static void gwps_leave_wps(bool theme_enabled)
 #ifdef HAVE_BACKDROP_IMAGE
             skin_backdrop_show(sb_get_backdrop(i));
 #endif
+            skin_update(CUSTOM_STATUSBAR, i, SKIN_REFRESH_ALL);
             viewportmanager_theme_undo(i, skin_has_sbs(gwps));
         }
     }