Rover: Ignore landing message

APMrover2/GCS_Mavlink.cpp

@@ -487,6 +487,7 @@ bool GCS_MAVLINK_Rover::try_send_message(enum ap_message id)
     case MSG_GIMBAL_REPORT:
     case MSG_RPM:
     case MSG_POSITION_TARGET_GLOBAL_INT:
+    case MSG_LANDING:
         break;  // just here to prevent a warning
     }
     return true;