drbd: Fixed conn_lowest_minor

It actually returned the lowest volume number. While doing that
renamed a few wrongly named variables.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 18cd2ed..d903fb5 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -326,9 +326,9 @@
 static void conn_md_sync(struct drbd_tconn *tconn)
 {
 	struct drbd_conf *mdev;
-	int minor;
+	int vnr;
 
-	idr_for_each_entry(&tconn->volumes, mdev, minor)
+	idr_for_each_entry(&tconn->volumes, mdev, vnr)
 		drbd_md_sync(mdev);
 }