hal: fix no audio in qchat call with speaker as default device

HAL doesnt let voice calls start if the device is set to speaker
as voice calls generally start on devices other than speaker.
However QCHAT calls start by calling setForceUse and setting the
device to speaker.

Fix by updating a flag whenever device routing happens when
AUDIO_MODE_IN_CALL. Reset the flag when mode is AUDIO_MODE_NORMAL.

CRs-fixed: 596074
Change-Id: I546959d2b0123828562dba1f6439aa494a365c3f