slub: remove invalid reference to list iterator variable

If list_for_each_entry, etc complete a traversal of the list, the iterator
variable ends up pointing to an address at an offset from the list head,
and not a meaningful structure.  Thus this value should not be used after
the end of the iterator.  The patch replaces s->name by al->name, which is
referenced nearby.

This problem was found using Coccinelle (http://coccinelle.lip6.fr/

).

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Pekka Enberg <penberg@kernel.org>