Bluetooth: btintel: Introduce generic Intel Bluetooth support

The majority of Intel Bluetooth vendor commands are shared between USB
and UART transports. This creates a separate module that eventually
will hold all Intel specific commands, but for now just start with the
commands to change the Bluetooth public address and check for the
default address.

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