slab: convert cpu notifier to return encapsulate errno value

By the previous modification, the cpu notifier can return encapsulate
errno value.  This converts the cpu notifiers for slab.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slab.c

@@ -1321,7 +1321,7 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
 		mutex_unlock(&cache_chain_mutex);
 		break;
 	}
-	return err ? NOTIFY_BAD : NOTIFY_OK;
+	return notifier_from_errno(err);
 }
 
 static struct notifier_block __cpuinitdata cpucache_notifier = {