Hal: Support an external BT chip for HFP

When using an external BT chip, AUXPCM is used for audio in/out between
bt chip and audio codec. In that case, AUXCPM Hostless should be used
instead of INT_BT_HFP Hostless

Change-Id: I73ad8d67031885a194da6d3a5b08ef462cb33374
Signed-off-by: Uday Kishore Pasupuleti <upasupul@codeaurora.org>