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_linux.h b/fs/xfs/linux-2.6/xfs_linux.h
index f65a53f..6127e24 100644
--- a/fs/xfs/linux-2.6/xfs_linux.h
+++ b/fs/xfs/linux-2.6/xfs_linux.h
@@ -24,7 +24,7 @@
  * XFS_BIG_BLKNOS needs block layer disk addresses to be 64 bits.
  * XFS_BIG_INUMS requires XFS_BIG_BLKNOS to be set.
  */
-#if defined(CONFIG_LBD) || (BITS_PER_LONG == 64)
+#if defined(CONFIG_LBDAF) || (BITS_PER_LONG == 64)
 # define XFS_BIG_BLKNOS	1
 # define XFS_BIG_INUMS	1
 #else