USIE_IF_N_XFER
for (i = 0; i != USIE_IF_N_XFER; i++)
static const struct usb_config usie_if_config[USIE_IF_N_XFER] = {
USIE_IF_N_XFER, sc, &sc->sc_mtx);
usbd_transfer_unsetup(sc->sc_if_xfer, USIE_IF_N_XFER);
usbd_transfer_unsetup(sc->sc_if_xfer, USIE_IF_N_XFER);
struct usb_xfer *sc_if_xfer[USIE_IF_N_XFER];