Merge pull request #12941 from kjbracey-arm/chrono-timeout-fix

Correct Timeout rescheduling

drivers/source/Timeout.cpp

@@ -27,11 +27,15 @@ namespace mbed {
 void TimeoutBase::handler()
 {
  if (_function) {
+ Callback<void()> function_to_call = _function;
+ // Clean up state to "detached" before calling callback; it may attach
+ // a new callback. Equivalent to detach(), but skips the remove();
+ // it's unnecessary because we're in the ticker's handler.
+ _function = nullptr;
  if (_lock_deepsleep) {
  sleep_manager_unlock_deep_sleep();
  }
- _function();
- _function = nullptr;
+ function_to_call();
  }
 }