manual_control: add instance to selector

This instance is then used to schedule the callback for the
subscription.

src/modules/manual_control/ManualControl.hpp

@@ -98,6 +98,7 @@ private:
 
 	ManualControlSelector _selector;
 	bool _published_invalid_once{false};
+	int _last_selected_input{-1};
 
 	perf_counter_t	_loop_perf{perf_alloc(PC_ELAPSED, MODULE_NAME": cycle")};
 	perf_counter_t	_loop_interval_perf{perf_alloc(PC_INTERVAL, MODULE_NAME": interval")};