hal: Support an external BT chip for HFP

Change mixer control name to 'PRI AUXPCM LOOPBACK Volume'
from 'Internal HFP RX Volume' for HFP which is using
external BT chip

Bug: 23349895
Change-Id: Ib509027ea36ece2ca17584af0664507f99263df4
Signed-off-by: Uday Kishore Pasupuleti <upasupul@codeaurora.org>