iwn_scan
if ((error = iwn_scan(sc, IEEE80211_CHAN_2GHZ, 0)) != 0) {
int iwn_scan(struct iwn_softc *, uint16_t, int);
error = iwn_scan(sc, IEEE80211_CHAN_5GHZ,
error = iwn_scan(sc, IEEE80211_CHAN_2GHZ, 1);