mtd: introduce mtd_write_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/nand/sm_common.c b/drivers/mtd/nand/sm_common.c
index 32ae5af..774c3c2 100644
--- a/drivers/mtd/nand/sm_common.c
+++ b/drivers/mtd/nand/sm_common.c
@@ -55,7 +55,7 @@
 	ops.datbuf = NULL;
 
 
-	ret = mtd->write_oob(mtd, ofs, &ops);
+	ret = mtd_write_oob(mtd, ofs, &ops);
 	if (ret < 0 || ops.oobretlen != SM_OOB_SIZE) {
 		printk(KERN_NOTICE
 			"sm_common: can't mark sector at %i as bad\n",