BT: Synchronize Bond SM message processing and cleanup

Issue:
ANR while accessing bonded devices

Steps:
Bonding/unbonding while BT disabling.

RootCause:
Bond State Machine cleanup while processing of
a message cause a application exit because of
dereference of cleaned up objects.

Fix:
Serialize BondStateMachine cleanup and processing of messages

Test:
On OFF sanity and other bonding and unbonding related scenario

Bug: 147404785
Change-Id: I0f1be81fd9d596968883e9a6759a619dced50624