Bluetooth: btusb: support public address configuration for ath3012

Set hdev->set_bdaddr handler for ath3012. It sends the vendor specific HCI
command to change the public address. The change doesn't persist across
power cycle.

Signed-off-by: Toshi Kikuchi <toshik@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>