RT2560_BEACON_RING_COUNT
sc->bcnq.next = (sc->bcnq.next + 1) % RT2560_BEACON_RING_COUNT;
sc->bcnq.cur = (sc->bcnq.cur + 1) % RT2560_BEACON_RING_COUNT;
error = rt2560_alloc_tx_ring(sc, &sc->bcnq, RT2560_BEACON_RING_COUNT);