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/tests/mtd_stresstest.c b/drivers/mtd/tests/mtd_stresstest.c
index a204a9f..83a8437 100644
--- a/drivers/mtd/tests/mtd_stresstest.c
+++ b/drivers/mtd/tests/mtd_stresstest.c
@@ -153,7 +153,7 @@
 			len = mtd->erasesize - offs;
 	}
 	addr = eb * mtd->erasesize + offs;
-	err = mtd->read(mtd, addr, len, &read, readbuf);
+	err = mtd_read(mtd, addr, len, &read, readbuf);
 	if (mtd_is_bitflip(err))
 		err = 0;
 	if (unlikely(err || read != len)) {