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/mtdpart.c b/drivers/mtd/mtdpart.c
index 0e7dfc7..a3d44c3 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -335,7 +335,7 @@
 	if (ofs >= mtd->size)
 		return -EINVAL;
 	ofs += part->offset;
-	res = part->master->block_markbad(part->master, ofs);
+	res = mtd_block_markbad(part->master, ofs);
 	if (!res)
 		mtd->ecc_stats.badblocks++;
 	return res;