[Bluetooth] Fix USB disconnect handling of btusb driver

The USB transport specification for Bluetooth splits the ACL and SCO
handling into two separate interfaces. In Linux it possible to probe
and disconnect these interfaces independently. So make sure that both
interfaces are tightly bound together.

This fixes the suspend regression that some people have expierenced.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>