MHU_INTR_CLEAR
bus_write_4(sc->res[0], MHU_CHAN_RX_HP + MHU_INTR_CLEAR,
bus_write_4(sc->res[0], offset + MHU_INTR_CLEAR,
bus_write_4(sc->res[0], MHU_CHAN_RX_LP + MHU_INTR_CLEAR,