control_allocator: do not update params while armed

As a precaution

src/modules/control_allocator/ControlAllocator.cpp

@@ -270,7 +270,7 @@ ControlAllocator::Run()
 	perf_begin(_loop_perf);
 
 	// Check if parameters have changed
-	if (_parameter_update_sub.updated()) {
+	if (_parameter_update_sub.updated() && !_armed) {
 		// clear update
 		parameter_update_s param_update;
 		_parameter_update_sub.copy(&param_update);
@@ -287,6 +287,8 @@ ControlAllocator::Run()
 
 	if (_vehicle_status_sub.update(&vehicle_status)) {
 
+		_armed = vehicle_status.arming_state == vehicle_status_s::ARMING_STATE_ARMED;
+
 		ActuatorEffectiveness::FlightPhase flight_phase{ActuatorEffectiveness::FlightPhase::HOVER_FLIGHT};
 
 		// Check if the current flight phase is HOVER or FIXED_WING

src/modules/control_allocator/ControlAllocator.hpp

@@ -173,6 +173,7 @@ private:
 
 	perf_counter_t	_loop_perf;			/**< loop duration performance counter */
 
+	bool _armed{false};
 	hrt_abstime _last_run{0};
 	hrt_abstime _timestamp_sample{0};
 	hrt_abstime _last_status_pub{0};