mtd: introduce mtd_block_markbad 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/ubi/io.c b/drivers/mtd/ubi/io.c
index a1b683a..5cde4e5 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -669,7 +669,7 @@
 	if (!ubi->bad_allowed)
 		return 0;
 
-	err = mtd->block_markbad(mtd, (loff_t)pnum * ubi->peb_size);
+	err = mtd_block_markbad(mtd, (loff_t)pnum * ubi->peb_size);
 	if (err)
 		ubi_err("cannot mark PEB %d bad, error %d", pnum, err);
 	return err;