Bluetooth: Enable Bluetooth Tethering interface for Bluedroid

Enable Bluetooth Tethering interface to support Bluetooth PAN
on Bluedroid.

Change-Id: Ia164300ad0aa86c7bd6e603e7c88f47e45a712a7
CRs-fixed: 443775

Conflicts:
	overlay/frameworks/base/core/res/res/values/config.xml