fix mqtt::on_message, #1494

lib/framework/ESP8266React.h

@@ -66,9 +66,6 @@ class ESP8266React {
     void setWill(const char * will_topic) {
         _mqttSettingsService.setWill(will_topic);
     }
-    void onMessage(espMqttClientTypes::OnMessageCallback callback) {
-        _mqttSettingsService.onMessage(callback);
-    }
 
     void factoryReset() {
         _factoryResetService.factoryReset();