AP_HAL_Empty: move delay callback handling to base HAL Scheduler class

libraries/AP_HAL_Empty/Scheduler.cpp

@@ -19,10 +19,6 @@ void Scheduler::delay(uint16_t ms)
 void Scheduler::delay_microseconds(uint16_t us)
 {}
 
-void Scheduler::register_delay_callback(AP_HAL::Proc k,
-            uint16_t min_time_ms)
-{}
-
 void Scheduler::register_timer_process(AP_HAL::MemberProc k)
 {}
 

libraries/AP_HAL_Empty/Scheduler.h

@@ -8,9 +8,6 @@ public:
     void     init();
     void     delay(uint16_t ms);
     void     delay_microseconds(uint16_t us);
-    void     register_delay_callback(AP_HAL::Proc,
-                uint16_t min_time_ms);
-
     void     register_timer_process(AP_HAL::MemberProc);
     void     register_io_process(AP_HAL::MemberProc);
     void     suspend_timer_procs();