mtd: introduce mtd_lock interface

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
index cc2336e..97d6360 100644
--- a/drivers/mtd/mtdconcat.c
+++ b/drivers/mtd/mtdconcat.c
@@ -556,7 +556,7 @@
 			size = len;
 
 		if (subdev->lock) {
-			err = subdev->lock(subdev, ofs, size);
+			err = mtd_lock(subdev, ofs, size);
 			if (err)
 				break;
 		} else