SLUB: Remove duplicate VM_BUG_ON

Somehow this artifact got in during merge with mm.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.21-rc7-mm1/mm/slub.c
===================================================================
--- linux-2.6.21-rc7-mm1.orig/mm/slub.c	2007-04-25 09:48:40.000000000 -0700
+++ linux-2.6.21-rc7-mm1/mm/slub.c	2007-04-25 09:48:47.000000000 -0700
@@ -633,8 +633,6 @@ static void add_full(struct kmem_cache *
 
 	VM_BUG_ON(!irqs_disabled());
 
-	VM_BUG_ON(!irqs_disabled());
-
 	if (!(s->flags & SLAB_STORE_USER))
 		return;