ar5416GetTsf64
extern uint64_t ar5416GetTsf64(struct ath_hal *ah);
ah->ah_getTsf64 = ar5416GetTsf64;
tsf = ar5416GetTsf64(ah);
if (AR_SREV_HOWL(ah) && (ar5416GetTsf64(ah) < tsf)) {
ichan->tsf_last = ar5416GetTsf64(ah);