md: Export and rename find_rdev_nr_rcu

This is required by the clustering module (patches to follow) to
find the device to remove or re-add.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.h b/drivers/md/md.h
index d98c0d7..ecdce36 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -672,6 +672,7 @@
 extern void md_reload_sb(struct mddev *mddev);
 extern void md_update_sb(struct mddev *mddev, int force);
 extern void md_kick_rdev_from_array(struct md_rdev * rdev);
+struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
 static inline int mddev_check_plugged(struct mddev *mddev)
 {
 	return !!blk_check_plugged(md_unplug, mddev,