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/tests/mtd_readtest.c b/drivers/mtd/tests/mtd_readtest.c
index 0c58d29..5eaeada 100644
--- a/drivers/mtd/tests/mtd_readtest.c
+++ b/drivers/mtd/tests/mtd_readtest.c
@@ -74,7 +74,7 @@
 			ops.ooboffs   = 0;
 			ops.datbuf    = NULL;
 			ops.oobbuf    = oobbuf;
-			ret = mtd->read_oob(mtd, addr, &ops);
+			ret = mtd_read_oob(mtd, addr, &ops);
 			if ((ret && !mtd_is_bitflip(ret)) ||
 					ops.oobretlen != mtd->oobsize) {
 				printk(PRINT_PREF "error: read oob failed at "