mavlink: don't send gimbal_device_attitude_status

If we receive gimbal_device_attitude_status by mavlink we should not
re-send it as we are already supposed to be forwarding mavlink traffic
from the gimbal to the ground station.

msg/gimbal_device_attitude_status.msg

@@ -16,3 +16,5 @@ float32 angular_velocity_y
 float32 angular_velocity_z
 
 uint32 failure_flags
+
+bool received_from_mavlink

src/modules/mavlink/mavlink_receiver.cpp

@@ -3070,6 +3070,8 @@ MavlinkReceiver::handle_message_gimbal_device_attitude_status(mavlink_message_t
 	gimbal_attitude_status.angular_velocity_z = gimbal_device_attitude_status_msg.angular_velocity_z;
 	gimbal_attitude_status.failure_flags = gimbal_device_attitude_status_msg.failure_flags;
 
+	gimbal_attitude_status.received_from_mavlink = true;
+
 	_gimbal_device_attitude_status_pub.publish(gimbal_attitude_status);
 }
 

src/modules/mavlink/streams/GIMBAL_DEVICE_ATTITUDE_STATUS.hpp

@@ -66,6 +66,14 @@ private:
 		gimbal_device_attitude_status_s gimbal_device_attitude_status{};
 
 		if (_gimbal_device_attitude_status_sub.update(&gimbal_device_attitude_status)) {
+
+			if (gimbal_device_attitude_status.received_from_mavlink) {
+				// If we have already received the gimbal device's attitude via
+				// mavlink it is already forwarded directly and we don't need
+				// to re-publish it here.
+				return false;
+			}
+
 			mavlink_gimbal_device_attitude_status_t msg{};
 
 			msg.target_system = gimbal_device_attitude_status.target_system;