Plane: fix build with new mavlink repo

ArduPlane/system.pde

@@ -180,7 +180,6 @@ static void init_ardupilot()
 
     //mavlink_system.sysid = MAV_SYSTEM_ID;				// Using g.sysid_this_mav
     mavlink_system.compid = 1;          //MAV_COMP_ID_IMU;   // We do not check for comp id
-    mavlink_system.type = MAV_TYPE_FIXED_WING;
 
     init_rc_in();               // sets up rc channels from radio
     init_rc_out();              // sets up the timer libs