ath_chanctx_get_next
prev = ath_chanctx_get_next(sc, cur);
ctx = ath_chanctx_get_next(sc, sc->cur_chan);
sc->next_chan = ath_chanctx_get_next(sc, sc->cur_chan);
sc->next_chan = ath_chanctx_get_next(sc, sc->cur_chan);
ctx = ath_chanctx_get_next(sc, sc->cur_chan);