rate limit most parameter_update subscriptions

- parameter updates can be quite expensive because they trigger nearly all modules to reload all of their parameters immediately
 - limit modules from updating faster than once per second

src/modules/mc_att_control/mc_att_control.hpp

@@ -58,6 +58,8 @@
 
 #include <AttitudeControl.hpp>
 
+using namespace time_literals;
+
 /**
  * Multicopter attitude control app start / stop handling function
  */
@@ -98,10 +100,11 @@ private:
 
 	AttitudeControl _attitude_control; ///< class for attitude control calculations
 
+	uORB::SubscriptionInterval _parameter_update_sub{ORB_ID(parameter_update), 1_s};
+
 	uORB::Subscription _vehicle_attitude_setpoint_sub{ORB_ID(vehicle_attitude_setpoint)};
 	uORB::Subscription _v_rates_sp_sub{ORB_ID(vehicle_rates_setpoint)};		/**< vehicle rates setpoint subscription */
 	uORB::Subscription _v_control_mode_sub{ORB_ID(vehicle_control_mode)};		/**< vehicle control mode subscription */
-	uORB::Subscription _params_sub{ORB_ID(parameter_update)};			/**< parameter updates subscription */
 	uORB::Subscription _manual_control_setpoint_sub{ORB_ID(manual_control_setpoint)};	/**< manual control setpoint subscription */
 	uORB::Subscription _vehicle_status_sub{ORB_ID(vehicle_status)};			/**< vehicle status subscription */
 	uORB::Subscription _vehicle_land_detected_sub{ORB_ID(vehicle_land_detected)};	/**< vehicle land detected subscription */

src/modules/mc_att_control/mc_att_control_main.cpp

@@ -228,10 +228,10 @@ MulticopterAttitudeControl::Run()
 	perf_begin(_loop_perf);
 
 	// Check if parameters have changed
-	if (_params_sub.updated()) {
+	if (_parameter_update_sub.updated()) {
 		// clear update
 		parameter_update_s param_update;
-		_params_sub.copy(&param_update);
+		_parameter_update_sub.copy(&param_update);
 
 		updateParams();
 		parameters_updated();