Update src/ArduinoIoTCloudTCP.cpp

Co-authored-by: Mattia Pennasilico <m.pennasilico@arduino.cc>

src/ArduinoIoTCloudTCP.cpp

@@ -303,6 +303,7 @@ ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_Connected()
     return State::Disconnect;
   }
 
+  /* Check for new data from the MQTT client. */
   _mqttClient.poll();
   /* Retransmit data in case there was a lost transaction due
    * to phy layer or MQTT connectivity loss.