Revert "[PATCH] USB: move usb_device_class class devices to be real devices"

This reverts c182274f commit because it
required a newer version of udev to work properly than what is currently
documented in Documentation/Changes.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>