Plane: increase update_waypoint() distance threshold during update_loiter()

- outside this radius of a loiter waypoint is where crosstracking is available

ArduPlane/navigation.cpp

@@ -185,7 +185,7 @@ void Plane::update_loiter(uint16_t radius)
     } else if (loiter.start_time_ms == 0 &&
         control_mode == AUTO &&
         !auto_state.no_crosstrack &&
-        get_distance(current_loc, next_WP_loc) > radius*2) {
+        get_distance(current_loc, next_WP_loc) > radius*3) {
         // if never reached loiter point and using crosstrack and somewhat far away from loiter point
         // navigate to it like in auto-mode for normal crosstrack behavior
         nav_controller->update_waypoint(prev_WP_loc, next_WP_loc);