sabrina: Configure Broadcom Bluetooth/Wi-Fi HALs

sabrina: Configure Broadcom Bluetooth/Wi-Fi HALs

* We're not unifying things, and the stock MultiHAL requires
  framework side magic, so we're going with the hardware/broadcom
  solution.

* Set Bluetooth overlays based on stock.

* bdroid_buildcfg header and vnd_$device.txt configuration are
  loosely taken from OEM uploads of Amlogic BCM Wi-Fi/BT device
  sources.

* Unlike all other g12a devices, sabrina sets ro.bt.bdaddr_path
  on stock to `/sys/class/bt_addr/value`.

Change-Id: Ie8e0f2d2a5f1cb8337ebe88b903fb18a71602f18