Fix WiFi.persistent(false); having no effect. (espressif#1406)

This PR calls `esp_wifi_set_storage(WIFI_STORAGE_RAM);` when persistent WiFi configuration is not desired.

Author: everslick

libraries/WiFi/src/WiFiGeneric.cpp

@@ -108,7 +108,7 @@ void tcpipInit(){
  }
 }
 
-static bool wifiLowLevelInit(){
+static bool wifiLowLevelInit(bool persistent){
  static bool lowLevelInitDone = false;
  if(!lowLevelInitDone){
  tcpipInit();
@@ -118,7 +118,9 @@ static bool wifiLowLevelInit(){
  log_e("esp_wifi_init %d", err);
  return false;
  }
- esp_wifi_set_storage(WIFI_STORAGE_FLASH);
+ if(!persistent){
+ esp_wifi_set_storage(WIFI_STORAGE_RAM);
+ }
  esp_wifi_set_mode(WIFI_MODE_NULL);
  lowLevelInitDone = true;
  }
@@ -133,11 +135,11 @@ static bool wifiLowLevelDeinit(){
 
 static bool _esp_wifi_started = false;
 
-static bool espWiFiStart(){
+static bool espWiFiStart(bool persistent){
  if(_esp_wifi_started){
  return true;
  }
- if(!wifiLowLevelInit()){
+ if(!wifiLowLevelInit(persistent)){
  return false;
  }
  esp_err_t err = esp_wifi_start();
@@ -383,7 +385,7 @@ bool WiFiGenericClass::mode(wifi_mode_t m)
  return false;
  }
  if(m){
- return espWiFiStart();
+ return espWiFiStart(_persistent);
  }
  return espWiFiStop();
 }
@@ -394,7 +396,7 @@ bool WiFiGenericClass::mode(wifi_mode_t m)
  */
 wifi_mode_t WiFiGenericClass::getMode()
 {
- if(!wifiLowLevelInit()){
+ if(!wifiLowLevelInit(_persistent)){
  return WIFI_MODE_MAX;
  }
  uint8_t mode;