changed naming

Author: naichenzhao

core/platform/lf_STM32f4_support.c

@@ -194,7 +194,7 @@ int lf_enable_interrupts_nested() {
     return 0;
 }
 
-int _lf_unthreaded_notify_of_event() {
+int _lf_single_threaded_notify_of_event() {
     _lf_async_event = true;
     return 0;
 }