vehicle_command topic: use uorb queuing with length 3

Just to make sure we don't lose any messages.

src/drivers/camera_trigger/camera_trigger.cpp

@@ -395,7 +395,7 @@ CameraTrigger::test()
 	cmd.param5 = 1.0f;
 
 	orb_advert_t pub;
-	pub = orb_advertise(ORB_ID(vehicle_command), &cmd);
+	pub = orb_advertise_queue(ORB_ID(vehicle_command), &cmd, vehicle_command_s::ORB_QUEUE_LENGTH);
 	(void)orb_unadvertise(pub);
 }
 

src/drivers/px4io/px4io.cpp

@@ -825,7 +825,7 @@ PX4IO::init()
 		cmd.confirmation =  1;
 
 		/* send command once */
-		orb_advert_t pub = orb_advertise(ORB_ID(vehicle_command), &cmd);
+		orb_advert_t pub = orb_advertise_queue(ORB_ID(vehicle_command), &cmd, vehicle_command_s::ORB_QUEUE_LENGTH);
 
 		/* spin here until IO's state has propagated into the system */
 		do {

src/drivers/vmount/input_mavlink.cpp

@@ -302,9 +302,14 @@ void InputMavlinkCmdMount::_ack_vehicle_command(uint16_t command)
 	vehicle_command_ack.command = command;
 	vehicle_command_ack.result = vehicle_command_s::VEHICLE_CMD_RESULT_ACCEPTED;
 
-	int instance;
-	orb_publish_auto(ORB_ID(vehicle_command_ack), &_vehicle_command_ack_pub, &vehicle_command_ack,
-			 &instance, ORB_PRIO_DEFAULT);
+	if (_vehicle_command_ack_pub == nullptr) {
+		_vehicle_command_ack_pub = orb_advertise_queue(ORB_ID(vehicle_command_ack), &vehicle_command_ack,
+					   vehicle_command_ack_s::ORB_QUEUE_LENGTH);
+
+	} else {
+		orb_publish(ORB_ID(vehicle_command_ack), _vehicle_command_ack_pub, &vehicle_command_ack);
+	}
+
 }
 
 void InputMavlinkCmdMount::print_status()

src/drivers/vmount/output_mavlink.cpp

@@ -75,7 +75,8 @@ int OutputMavlink::update(const ControlData *control_data)
 			orb_publish(ORB_ID(vehicle_command), _vehicle_command_pub, &vehicle_command);
 
 		} else {
-			_vehicle_command_pub = orb_advertise_queue(ORB_ID(vehicle_command), &vehicle_command, 3);
+			_vehicle_command_pub = orb_advertise_queue(ORB_ID(vehicle_command), &vehicle_command,
+					       vehicle_command_s::ORB_QUEUE_LENGTH);
 		}
 
 	}