USB: sierra: fix urbs not being killed on shutdown

Make sure to stop all I/O, including any active write urbs, at shutdown.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/sierra.c

@@ -813,6 +813,8 @@ static void sierra_close(struct usb_serial_port *port)
 	}
 
 	sierra_stop_rx_urbs(port);
+	usb_kill_anchored_urbs(&portdata->active);
+
 	for (i = 0; i < portdata->num_in_urbs; i++) {
 		sierra_release_urb(portdata->in_urbs[i]);
 		portdata->in_urbs[i] = NULL;