Plane: remove quadplane calls to multicopter poscontrol's freeze_ff_xy

ArduPlane/quadplane.cpp

@@ -1799,8 +1799,6 @@ void QuadPlane::vtol_position_controller(void)
         const Vector3f& curr_pos = inertial_nav.get_position();
         pos_control->set_xy_target(curr_pos.x, curr_pos.y);
         
-        pos_control->freeze_ff_xy();
-        
         // nav roll and pitch are controller by position controller
         plane.nav_roll_cd = pos_control->get_roll();
         plane.nav_pitch_cd = pos_control->get_pitch();