block/Kconfig: Make the BLK_WBT and BLK_WBT_MQ entries consecutive

These entries were consecutive at the time of their introduction but are no
longer consecutive. Make these again consecutive. Additionally, modify the
help text since it refers to blk-mq and since the legacy block layer has
been removed.

Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Link: https://lore.kernel.org/r/20210618004456.7280-2-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/Kconfig

@@ -133,6 +133,13 @@ config BLK_WBT
 	dynamically on an algorithm loosely based on CoDel, factoring in
 	the realtime performance of the disk.
 
+config BLK_WBT_MQ
+	bool "Enable writeback throttling by default"
+	default y
+	depends on BLK_WBT
+	help
+	Enable writeback throttling by default for request-based block devices.
+
 config BLK_CGROUP_IOLATENCY
 	bool "Enable support for latency based cgroup IO protection"
 	depends on BLK_CGROUP=y
@@ -155,13 +162,6 @@ config BLK_CGROUP_IOCOST
 	distributes IO capacity between different groups based on
 	their share of the overall weight distribution.
 
-config BLK_WBT_MQ
-	bool "Multiqueue writeback throttling"
-	default y
-	depends on BLK_WBT
-	help
-	Enable writeback throttling by default on multiqueue devices.
-
 config BLK_DEBUG_FS
 	bool "Block layer debugging information in debugfs"
 	default y