AP_HAL_ChibiOS: rename system_initialized() and add is_system_initialized()

libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp

@@ -236,7 +236,7 @@ static void main_loop()
 
     schedulerInstance.watchdog_pat();
 
-    hal.scheduler->system_initialized();
+    hal.scheduler->set_system_initialized();
 
     thread_running = true;
     chRegSetThreadName(SKETCHNAME);

libraries/AP_HAL_ChibiOS/Scheduler.cpp

@@ -565,10 +565,10 @@ void Scheduler::_storage_thread(void* arg)
     }
 }
 
-void Scheduler::system_initialized()
+void Scheduler::set_system_initialized()
 {
     if (_initialized) {
-        AP_HAL::panic("PANIC: scheduler::system_initialized called"
+        AP_HAL::panic("PANIC: scheduler::set_system_initialized called"
                       "more than once");
     }
     _initialized = true;

libraries/AP_HAL_ChibiOS/Scheduler.h

@@ -92,7 +92,8 @@ public:
 
     bool     in_main_thread() const override { return get_main_thread() == chThdGetSelfX(); }
 
-    void     system_initialized() override;
+    void     set_system_initialized() override;
+    bool     is_system_initialized() override { return _initialized; };
     void     hal_initialized() { _hal_initialized = true; }
 
     bool     check_called_boost(void);