hw_features: Clean center freq for falling back HT40 channels

Some channels fail to be set, when falling back to 20 MHz, due to
remaining VHT info of center freq. As we are going to 20 MHz, reset the
VHT center frequency segment information as well.

Signed-off-by: Eduardo Abinader <eduardoabinader@gmail.com>

src/ap/hw_features.c

@@ -329,6 +329,8 @@ static void ieee80211n_check_scan(struct hostapd_iface *iface)
 	res = ieee80211n_allowed_ht40_channel_pair(iface);
 	if (!res) {
 		iface->conf->secondary_channel = 0;
+		iface->conf->vht_oper_centr_freq_seg0_idx = 0;
+		iface->conf->vht_oper_centr_freq_seg1_idx = 0;
 		res = 1;
 		wpa_printf(MSG_INFO, "Fallback to 20 MHz");
 	}