proper prototype for blk_dev_init()

This patch adds a proper prototye for blk_dev_init() in block/blk.h

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk.h b/block/blk.h
index ec898dd..ec9120f 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -32,6 +32,8 @@
 
 void blk_queue_congestion_threshold(struct request_queue *q);
 
+int blk_dev_init(void);
+
 /*
  * Return the threshold (number of used requests) at which the queue is
  * considered to be congested.  It include a little hysteresis to keep the