AP_NavEKF3: fixed scary message for non-compass planes

libraries/AP_NavEKF3/AP_NavEKF3_MagFusion.cpp

@@ -1498,7 +1498,7 @@ bool NavEKF3_core::EKFGSF_resetMainFilterYaw()
         EKFGSF_yaw_reset_ms = imuSampleTime_ms;
         EKFGSF_yaw_reset_count++;
 
-        if (effectiveMagCal == MagCal::GSF_YAW) {
+        if (effectiveMagCal == MagCal::GSF_YAW || AP::compass().get_num_enabled() == 0) {
             gcs().send_text(MAV_SEVERITY_INFO, "EKF3 IMU%u yaw aligned using GPS",(unsigned)imu_index);
         } else {
             gcs().send_text(MAV_SEVERITY_WARNING, "EKF3 IMU%u emergency yaw reset - mag sensor stopped",(unsigned)imu_index);