TWSP-A2DP: set active device to null if setA2dpActive to peer earbud failed

In some race condition, while EB1 get disconnected, and activeDeviceManager attempt
to set active a2dp device to peer earbud(EB2), but while a2dp service set active
device, EB2 get disconnected in a2dp stateMachine, so that set EB2 as a2dp active
device failed and mActiveA2dpDevice is still EB1, then activeDeviceManager handle
for disconnected event from EB2, it will not attempt to set active to null. After
that earbuds reconnect, but btif av will not set any earbud to current playing
device.

Change-Id: Ie0782bb8af37b5059d8c708624b54ca1c7893fad
CRs-fixed: 2480094
1 file changed