FlightTaskManualPosition: simplify optical flow limiting logic

src/modules/flight_mode_manager/tasks/ManualPosition/FlightTaskManualPosition.cpp

@@ -89,10 +89,8 @@ void FlightTaskManualPosition::_scaleSticks()
 	float velocity_scale = _param_mpc_vel_manual.get();
 
 	if (PX4_ISFINITE(max_speed_from_estimator)) {
-		// use the minimum of the estimator and user specified limit
-		velocity_scale = fminf(velocity_scale, max_speed_from_estimator);
-		// Allow for a minimum of 0.3 m/s for repositioning
-		velocity_scale = fmaxf(velocity_scale, 0.3f);
+		// Constrain with optical flow limit but leave 0.3 m/s for repositioning
+		velocity_scale = math::constrain(velocity_scale, 0.3f, max_speed_from_estimator);
 	}
 
 	// scale velocity to its maximum limits