bluez: Add Bluetooth bluez mixin

Bluetooth bluez mixin offers alternative stack developed by Intel. More
information is in README.

Change-Id: I536f16dd50ee855b0885c638a235c62bf499cb1c
android-bluez: Source bluetooth firmware makefile

Change-Id: I57fdafd1624ee2d310070420a1836c59bb119669
bluez: Rename hsp audio device to sco

Change-Id: Iaccbb6aecaef09b1d2a2306a6678974e3ba2f3f4