Previous commit missed an unsupported-device-flash-LED check.

NOTE: Downstream's full-speed host controller is flakey when connecting
to low-speed devices. One mouse enumerates on only 50% of connection
events, while another mouse enumerates on 90% of connections. Grrr.

Downstream/Middlewares/ST/STM32_USB_Host_Library/Core/Src/usbh_core.c

@@ -541,6 +541,7 @@ USBH_StatusTypeDef  USBH_Process(USBH_HandleTypeDef *phost)
       }
       else
       {
+    	phost->pUser(phost, HOST_USER_CLASS_FAILED);
         phost->gState  = HOST_ABORT_STATE;
         USBH_UsrLog ("No registered class for this device.");
       }