SLUB: remove nr_cpu_ids hack

This was in SLUB in order to head off trouble while the nr_cpu_ids
functionality was not merged.  Its merged now so no need to still have this.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>