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/mtdchar.c b/drivers/mtd/mtdchar.c
index 922da31..e74f570 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -227,7 +227,7 @@
 			ops.oobbuf = NULL;
 			ops.len = len;
 
-			ret = mtd->read_oob(mtd, *ppos, &ops);
+			ret = mtd_read_oob(mtd, *ppos, &ops);
 			retlen = ops.retlen;
 			break;
 		}
@@ -471,7 +471,7 @@
 		return -ENOMEM;
 
 	start &= ~((uint64_t)mtd->writesize - 1);
-	ret = mtd->read_oob(mtd, start, &ops);
+	ret = mtd_read_oob(mtd, start, &ops);
 
 	if (put_user(ops.oobretlen, retp))
 		ret = -EFAULT;