BT: Multi HF support in bluedroid stack.

1. Add multi headset support in stack.
2. Each HS will be associated with unique CB in BTIF
and also corresponding SCB in BTA.
3. Upstream event callbacks will be sent to
specific HS based on BD_ADDR.
4. Similiarly all commands to BTIF will be for
specific HS.

Conflicts:

	btif/src/btif_multi_hf.c

Change-Id: Ia574dcb9e0798b826249a5d2389cd38720b0b983
Bluetooth: Handle Transient Audio Focus Lost

Changes made to Handler Transient Audio Focus in btif layer.

Change-Id: I7d25a4b9b13ea35784a8232617b9a8c0c55ec5b3
CRs-fixed: 590190
Revert "Fix building without BLE"

This reverts commit 0caf4a8aed29fd5e4e9be663f2f303b85b27e7f7.