PositionControl: handle yaw NAN inputs

src/modules/mc_pos_control/PositionControl/PositionControl.cpp

@@ -133,6 +133,9 @@ void PositionControl::update(const float dt)
 
 	_positionControl();
 	_velocityControl(dt);
+
+	_yawspeed_sp = PX4_ISFINITE(_yawspeed_sp) ? _yawspeed_sp : 0.f;
+	_yaw_sp = PX4_ISFINITE(_yaw_sp) ? _yaw_sp : _yaw; // TODO: better way to disable yaw control
 }
 
 bool PositionControl::_interfaceMapping()