slab: convert last use of __FUNCTION__ to __func__

Just about all of these have been converted to __func__, so convert the
last use.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slab.h

@@ -256,7 +256,7 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
 		return cachep;
 
 	pr_err("%s: Wrong slab cache. %s but object is from %s\n",
-		__FUNCTION__, cachep->name, s->name);
+	       __func__, cachep->name, s->name);
 	WARN_ON_ONCE(1);
 	return s;
 }