block: rename CONFIG_DEBUG_BLK_CGROUP to CONFIG_BFQ_CGROUP_DEBUG

This option is entirely bfq specific, give it an appropinquate name.

Also make it depend on CONFIG_BFQ_GROUP_IOSCHED in Kconfig, as all
the functionality already does so anyway.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index 4626b88..7a6b2f2 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -36,6 +36,13 @@
        Enable hierarchical scheduling in BFQ, using the blkio
        (cgroups-v1) or io (cgroups-v2) controller.
 
+config BFQ_CGROUP_DEBUG
+	bool "BFQ IO controller debugging"
+	depends on BFQ_GROUP_IOSCHED
+	---help---
+	Enable some debugging help. Currently it exports additional stat
+	files in a cgroup which can be useful for debugging.
+
 endmenu
 
 endif