bluedroid: add btmac tool

Load correct bluetooth MAC address from NV memory.
Based on Blefish's implementation.

Change-Id: I82ed8b351bd31c5061b552b41877055cdece8953
use bt-pan as bluetooth tethering interface

Change-Id: If0287a90decccc28e50dfeb6fbf710bab3cd2eb4
remove focal overlays

Focal camera is no longer part of CM.

Change-Id: Ie394f20dd90e0456a7ab4326dc75658c11f47c1c