ath_hal_pkt_txtime
extern uint32_t __ahdecl ath_hal_pkt_txtime(struct ath_hal *ah,
ctsduration += ath_hal_pkt_txtime(sc->sc_ah, rt, length, rix,
tt += (long_retries+1)*ath_hal_pkt_txtime(sc->sc_ah, rt, length, rix,
txtime = ath_hal_pkt_txtime(ah, rt, rs->rs_datalen,