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