Set alarm's queue to NULL on alarm expired

Use Case: Repeated BT ON/OFF

Failure: ANR due to race condition between random advertisement
address generation completion(adv_raddr_timer) and BT shutdown.

Steps: SNS Stress testing.

Root Cause: Race condition happens between random advertisement
address generation completion(adv_raddr_timer) and BT shutdown.

Fix:  For non-periodic alarms, set alarm's queue to NULL once alarm
expired.

Test: mm -j8

Change-Id: Idf8e2bebdc2ca7621aef06dd5f2075ef2c5fa08c

system/osi/src/alarm.cc

@@ -563,6 +563,7 @@ static void alarm_queue_ready(fixed_queue_t* queue, UNUSED_ATTR void* context) {
     alarm->deadline = 0;
     alarm->callback = NULL;
     alarm->data = NULL;
+    alarm->queue = NULL;
   }
 
   std::lock_guard<std::recursive_mutex> cb_lock(*alarm->callback_mutex);