mtd: introduce mtd_write interface

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/fs/logfs/dev_mtd.c b/fs/logfs/dev_mtd.c
index 3ee6435..1842440 100644
--- a/fs/logfs/dev_mtd.c
+++ b/fs/logfs/dev_mtd.c
@@ -49,7 +49,7 @@
 	BUG_ON(len > PAGE_CACHE_SIZE);
 	page_start = ofs & PAGE_CACHE_MASK;
 	page_end = PAGE_CACHE_ALIGN(ofs + len) - 1;
-	ret = mtd->write(mtd, ofs, len, &retlen, buf);
+	ret = mtd_write(mtd, ofs, len, &retlen, buf);
 	if (ret || (retlen != len))
 		return -EIO;