preinitWiFiOff() is only required for ESP8266

ampel-firmware/ampel-firmware.ino

@@ -60,8 +60,9 @@
  * PreInit                                                       *
  *****************************************************************/
 void preinit() {
-#ifndef AMPEL_WIFI
-  // Disable wifi as default
+#if !defined(AMPEL_WIFI) && defined(ESP8266)
+  // WiFi would be initialized otherwise (on ESP8266), even if unused.
+  // see https://github.com/esp8266/Arduino/issues/2111#issuecomment-224251391
   ESP8266WiFiClass::preinitWiFiOff();
 #endif
 }