mm: slub: remove unused virt_to_obj()

It's unused since commit 7ed2f9e66385 ("mm, kasan: SLAB support")

Link: http://lkml.kernel.org/r/1464020961-2242-1-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/slub_def.h

@@ -111,22 +111,6 @@ static inline void sysfs_slab_remove(struct kmem_cache *s)
 }
 #endif
 
-
-/**
- * virt_to_obj - returns address of the beginning of object.
- * @s: object's kmem_cache
- * @slab_page: address of slab page
- * @x: address within object memory range
- *
- * Returns address of the beginning of object
- */
-static inline void *virt_to_obj(struct kmem_cache *s,
-				const void *slab_page,
-				const void *x)
-{
-	return (void *)x - ((x - slab_page) % s->size);
-}
-
 void object_err(struct kmem_cache *s, struct page *page,
 		u8 *object, char *reason);