Bluetooth: Check for default address of Broadcom BCM20702A0 controllers

The Broadcom BCM20702A0 USB controllers might come with the default
address 00:20:70:02:A0:00 when booting up. If this happens, then warn
about such address being used.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>