Fix issue with incorrect secondary_channel in HT40/HT80

When primary and secondary channel were switched and config was
reloaded, secondary channel was incorrectly overwritten.

Proceed as for other settings that should not be changed and don't
allow to overwrite.

Signed-off-by: Pawel Kulakowski <pawel.kulakowski@tieto.com>

src/ap/hostapd.c

@@ -172,6 +172,7 @@ int hostapd_reload_config(struct hostapd_iface *iface)
 		hapd = iface->bss[j];
 		hapd->iconf = newconf;
 		hapd->iconf->channel = oldconf->channel;
+		hapd->iconf->secondary_channel = oldconf->secondary_channel;
 		hapd->iconf->ieee80211n = oldconf->ieee80211n;
 		hapd->iconf->ieee80211ac = oldconf->ieee80211ac;
 		hapd->iconf->ht_capab = oldconf->ht_capab;