mtd: introduce mtd_read_oob 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/mtdswap.c b/drivers/mtd/mtdswap.c
index 6ff823e..0f0ab18 100644
--- a/drivers/mtd/mtdswap.c
+++ b/drivers/mtd/mtdswap.c
@@ -312,7 +312,7 @@
 static int mtdswap_read_oob(struct mtdswap_dev *d, loff_t from,
 			struct mtd_oob_ops *ops)
 {
-	int ret = d->mtd->read_oob(d->mtd, from, ops);
+	int ret = mtd_read_oob(d->mtd, from, ops);
 
 	if (mtd_is_bitflip(ret))
 		return ret;
@@ -955,7 +955,7 @@
 
 		pos = base;
 		for (i = 0; i < mtd_pages; i++) {
-			ret = mtd->read_oob(mtd, pos, &ops);
+			ret = mtd_read_oob(mtd, pos, &ops);
 			if (ret)
 				goto error;