Listen to BT audio off outside of calls

Previous change had made us stop listening to BT audio state changes
outside of calls. Turns out we need to keep listening for the audio-off
in case it comes in after we've cleared our calls list.

Fixes: 125493929
Test: manual
Change-Id: I0f7a25d5ba82748a7242343c664bd774bd6edb52
1 file changed