ath_hal_getchannoise
*noise = ath_hal_getchannoise(ah, ni->ni_chan);
nf = ath_hal_getchannoise(ah, sc->sc_curchan);
nf = ath_hal_getchannoise(ah, sc->sc_curchan);
nf = ath_hal_getchannoise(sc->sc_ah, sc->sc_curchan);