heightrate ff: fix order of calculations

src/lib/external_lgpl/tecs/tecs.cpp

@@ -236,9 +236,8 @@ void TECS::_update_height_demand(float demand, float state)
 //	// 	_hgt_rate_dem);
 
 	_hgt_dem_adj = demand;//0.025f * demand + 0.975f * _hgt_dem_adj_last;
-	_hgt_dem_adj_last = _hgt_dem_adj;
-
 	_hgt_rate_dem = (_hgt_dem_adj-state)*_heightrate_p + _heightrate_ff * (_hgt_dem_adj - _hgt_dem_adj_last)/_DT;
+	_hgt_dem_adj_last = _hgt_dem_adj;
 	// Limit height rate of change
 	if (_hgt_rate_dem > _maxClimbRate) {
 		_hgt_rate_dem = _maxClimbRate;