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/block/Kconfig b/block/Kconfig
index 2c39527..95a86ad 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -23,8 +23,8 @@
 
 if BLOCK
 
-config LBD
-	bool "Support for large block devices and files"
+config LBDAF
+	bool "Support for large (2TB+) block devices and files"
 	depends on !64BIT
 	default y
 	help