Used for AP+STA support in OpenWrt - preserve AP mode keys across STA reconnects

--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -846,7 +846,6 @@ static int ieee80211_stop_ap(struct wiph
 	sdata->u.ap.driver_smps_mode = IEEE80211_SMPS_OFF;
 
 	__sta_info_flush(sdata, true);
-	ieee80211_free_keys(sdata, true);
 
 	sdata->vif.bss_conf.enable_beacon = false;
 	sdata->vif.bss_conf.ssid_len = 0;