attitude_estimator_q: no mavlink_log for QURT

Don't try to open the mavlink_fd on QURT because the px4_ioctl leads to
timeouts of the attitude_estimator_q loop.

src/modules/attitude_estimator_q/attitude_estimator_q_main.cpp

@@ -324,9 +324,12 @@ void AttitudeEstimatorQ::task_main()
 	while (!_task_should_exit) {
 		int ret = px4_poll(fds, 1, 1000);
 
+#ifndef __PX4_QURT
 		if (_mavlink_fd < 0) {
+			/* TODO: This call currently stalls the thread on QURT */
 			_mavlink_fd = open(MAVLINK_LOG_DEVICE, 0);
 		}
+#endif
 
 		if (ret < 0) {
 			// Poll error, sleep and try again