dm io: clean interface

Clean up the dm-io interface to prepare for publishing it in include/linux.

Signed-off-by: Heinz Mauelshagen <hjm@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index f6b20de..14f785f 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -208,7 +208,7 @@
 	struct dm_dev *log_dev;
 	struct log_header header;
 
-	struct io_region header_location;
+	struct dm_io_region header_location;
 	struct log_header *disk_header;
 };