fix commander: avoid LED printf errors on every SITL startup

src/modules/commander/Commander.cpp

@@ -1196,13 +1196,8 @@ Commander::run()
 	param_t _param_rc_map_arm_switch = param_find("RC_MAP_ARM_SW");
 
 	/* initialize */
-	if (led_init() != OK) {
-		PX4_WARN("LED init failed");
-	}
-
-	if (buzzer_init() != OK) {
-		PX4_WARN("Buzzer init failed");
-	}
+	led_init();
+	buzzer_init();
 
 	{
 		// we need to do an initial publication to make sure uORB allocates the buffer, which cannot happen

src/modules/commander/commander_helper.cpp

@@ -296,8 +296,9 @@ int led_init()
 	fd_leds = px4_open(LED0_DEVICE_PATH, O_RDWR);
 
 	if (fd_leds < 0) {
-		PX4_ERR("LED: open %s failed", LED0_DEVICE_PATH);
-		return PX4_ERROR;
+		// there might not be an LED available, so don't make this an error
+		PX4_INFO("LED: open %s failed (%i)", LED0_DEVICE_PATH, errno);
+		return -errno;
 	}
 
 	/* the green LED is only available on FMUv5 */