MC stabilized: allow yaw control at 0 throttle if yaw-airmode is selected

src/modules/mc_att_control/mc_att_control.hpp

@@ -269,7 +269,9 @@ private:
 		(ParamFloat<px4::params::MPC_MANTHR_MIN>) _man_throttle_min,			/**< minimum throttle for stabilized */
 		(ParamFloat<px4::params::MPC_THR_MAX>) _throttle_max,				/**< maximum throttle for stabilized */
 		(ParamFloat<px4::params::MPC_THR_HOVER>) _throttle_hover,			/**< throttle at which vehicle is at hover equilibrium */
-		(ParamInt<px4::params::MPC_THR_CURVE>) _throttle_curve				/**< throttle curve behavior */
+		(ParamInt<px4::params::MPC_THR_CURVE>) _throttle_curve,				/**< throttle curve behavior */
+
+		(ParamInt<px4::params::MC_AIRMODE>) _airmode
 	)
 
 	matrix::Vector3f _attitude_p;		/**< P gain for attitude control */

src/modules/mc_att_control/mc_att_control_main.cpp

@@ -438,7 +438,7 @@ MulticopterAttitudeControl::generate_attitude_setpoint(float dt, bool reset_yaw_
 	if (reset_yaw_sp) {
 		_man_yaw_sp = yaw;
 
-	} else if (_manual_control_sp.z > 0.05f) {
+	} else if (_manual_control_sp.z > 0.05f || _airmode.get() == (int32_t)Mixer::Airmode::roll_pitch_yaw) {
 
 		const float yaw_rate = math::radians(_yaw_rate_scaling.get());
 		attitude_setpoint.yaw_sp_move_rate = _manual_control_sp.r * yaw_rate;