microRTPS_transport: replace printf() with PX4_ERR()

msg/templates/urtps/microRTPS_transport.cpp

 /****************************************************************************
  *
  * Copyright 2017 Proyectos y Sistemas de Mantenimiento SL (eProsima).
+ * Copyright (c) 2018-2019 PX4 Development Team. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -309,7 +310,7 @@ int UART_node::init()
 		speed_t speed;
 
 		if (!baudrate_to_speed(baudrate, &speed)) {
-			printf("ERR SET BAUD %s: Unsupported baudrate: %d\n\tsupported examples:\n\t9600, 19200, 38400, 57600, 115200, 230400, 460800, 500000, 921600, 1000000\n",
+			PX4_ERR("ERR SET BAUD %s: Unsupported baudrate: %d\n\tsupported examples:\n\t9600, 19200, 38400, 57600, 115200, 230400, 460800, 500000, 921600, 1000000\n",
 			       uart_name, baudrate);
 			close();
 			return -EINVAL;