HFP: Synchronize the state machine while sending call state

Synchronizing the state machine for a particular device while
sending the call state information during addition/removal of
the state machine object in the state machine hashmap.

This avoids the case when a message is sent to state machine
while the state machine object is removed.

CRs-Fixed: 2388742
Change-Id: Ie448f076375ce67dba8c0df96d8b9c98cfb7ed83
1 file changed