fixes esp8266#3793

wifi_softap_set_config always fails, password cannot be 0 unless authmode is open, no documentation found, trial and error.

Author: tablatronix

Diff for: libraries/ESP8266WiFi/src/ESP8266WiFiAP.cpp

@@ -265,6 +265,7 @@ bool ESP8266WiFiAPClass::softAPdisconnect(bool wifioff) {
     struct softap_config conf;
     *conf.ssid = 0;
     *conf.password = 0;
+    conf.authmode = AUTH_OPEN;
     ETS_UART_INTR_DISABLE();
     if(WiFi._persistent) {
         ret = wifi_softap_set_config(&conf);