Driver core: Cleanup get_device_parent() in device_add() and device_move()

Driver core: Cleanup get_device_parent() in device_add() and device_move()

Make setup_parent() void as get_device_parent() will always return
either a valid kobject or NULL.
Introduce cleanup_glue_dir() to drop reference grabbed on "glue"
directory by get_device_parent(). Use it for cleanup in device_move()
and device_add() on errors.

This should fix the refcounting problem reported in
http://marc.info/?l=linux-kernel&m=120052487909200&w=2

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Dave Young <hidave.darkstar@gmail.com>
Cc: Gabor Gombas <gombasg@sztaki.hu>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: David Miller <davem@davemloft.net>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>