blkcg: misc preparations for unified hierarchy interface

* Export blkg_dev_name()

* Drop unnecessary @cft from __cfq_set_weight().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 85a4d98..b270aef 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -182,6 +182,7 @@
 void blkcg_deactivate_policy(struct request_queue *q,
 			     const struct blkcg_policy *pol);
 
+const char *blkg_dev_name(struct blkcg_gq *blkg);
 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 		       u64 (*prfill)(struct seq_file *,
 				     struct blkg_policy_data *, int),