mtd: introduce mtd_read 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 b3895cf..4546034 100644
--- a/drivers/mtd/mtdconcat.c
+++ b/drivers/mtd/mtdconcat.c
@@ -91,7 +91,7 @@
 			/* Entire transaction goes into this subdev */
 			size = len;
 
-		err = subdev->read(subdev, from, size, &retsize, buf);
+		err = mtd_read(subdev, from, size, &retsize, buf);
 
 		/* Save information about bitflips! */
 		if (unlikely(err)) {