Protect audio communication device set/clear operations with a lock.

Currently, when telecom audio stack handle series messages relate to
communication device set/clear operations, these operations will be
completed in random order which will cause unexpected device set as the
communication device. Protect these operations with a lock to avoid race
conditions.

Bug: b/303001133
Test: atest CallAudioRouteStateMachineTest
Change-Id: Ib9fcbc712aaa3583ceea17288fa85ac33c0e7d3c