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/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
index efc0cb3..eae5be4 100644
--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -1101,7 +1101,7 @@
 	ops.len = ops.ooboffs = ops.retlen = ops.oobretlen = 0;
 	ops.datbuf = NULL;
 
-	ret = c->mtd->write_oob(c->mtd, jeb->offset, &ops);
+	ret = mtd_write_oob(c->mtd, jeb->offset, &ops);
 	if (ret || ops.oobretlen != ops.ooblen) {
 		printk(KERN_ERR "cannot write OOB for EB at %08x, requested %zd"
 				" bytes, read %zd bytes, error %d\n",