audio policy: use call screen mode

Enable playback over Call Tx path also when audio mode is CALL_SCREEN.
Was previously only possilbe when IN_CALL or IN_COMMUNICATION.

Also generalize use of isStateInCall() method instead of
a mix of isStateInCall() and is_state_in_call().

Bug: 140384450
Test: manual call screen test
Change-Id: Ifda4ee2f26a30ed8dbe43b172d86b18d906029cf
2 files changed