Staging: ipack/bridges/tpci200: delete ipack_device_unregister calls when exiting

As the ipack_bus_unregister() takes care of unregistering the devices plugged
in the carrier, it is not needed to do it in the carrier driver.

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>