mc_pos_control: timestamp fix for vel_sp

src/modules/mc_pos_control/mc_pos_control_main.cpp

@@ -1692,6 +1692,7 @@ MulticopterPositionControl::control_position(float dt)
 
 	_vel_sp_prev = _vel_sp;
 
+	_global_vel_sp.timestamp = hrt_absolute_time();
 	_global_vel_sp.vx = _vel_sp(0);
 	_global_vel_sp.vy = _vel_sp(1);
 	_global_vel_sp.vz = _vel_sp(2);