usbd_set_polling
usbd_set_polling(sc->sc_hdev.sc_udev, on);
usbd_set_polling(sc->sc_udev, 1);
usbd_set_polling(sc->sc_udev, 0);
usbd_set_polling(sc->sc_udev, 1);
usbd_set_polling(sc->sc_udev, 0);
void usbd_set_polling(struct usbd_device *iface, int on);