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/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index b01993e..e36191a 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -699,7 +699,8 @@
 		for (i=0; i<count; i++) {
 			if (!vecs[i].iov_len)
 				continue;
-			ret = mtd->write(mtd, to, vecs[i].iov_len, &thislen, vecs[i].iov_base);
+			ret = mtd_write(mtd, to, vecs[i].iov_len, &thislen,
+					vecs[i].iov_base);
 			totlen += thislen;
 			if (ret || thislen != vecs[i].iov_len)
 				break;