block: rename CONFIG_LBD to CONFIG_LBDAF

Follow-up to "block: enable by default support for large devices
and files on 32-bit archs".

Rename CONFIG_LBD to CONFIG_LBDAF to:
- allow update of existing [def]configs for "default y" change
- reflect that it is used also for large files support nowadays

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 2e09efb..a220d36 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -616,7 +616,7 @@
 	 */
 
 #if BITS_PER_LONG == 32
-# if defined(CONFIG_LBD)
+# if defined(CONFIG_LBDAF)
 	ASSERT(sizeof(sector_t) == 8);
 	pagefactor = PAGE_CACHE_SIZE;
 	bitshift = BITS_PER_LONG;