Change disconnect function (espressif#466)

* Change disconnect function Current implementation does not disconnect the WiFi. Use of `esp_wifi_disconnect()` does. * Update WiFiSTA.cpp put back the clear ssid + password remove the duplicate `esp_wifi_set_config(WIFI_IF_STA, &conf);`

Author: sticilface

libraries/WiFi/src/WiFiSTA.cpp

@@ -262,7 +262,7 @@ bool WiFiSTAClass::disconnect(bool wifioff)
  WiFi.getMode();
  esp_wifi_start();
  esp_wifi_set_config(WIFI_IF_STA, &conf);
- ret = esp_wifi_set_config(WIFI_IF_STA, &conf) == ESP_OK;
+ ret = esp_wifi_disconnect() == ESP_OK;
 
  if(wifioff) {
  WiFi.enableSTA(false);