[MTD] Initialize 'writesize'

Signed-off-by: Artem B. Bityutskiy <dedekind@infradead.org>
diff --git a/drivers/mtd/devices/ms02-nv.c b/drivers/mtd/devices/ms02-nv.c
index 4ab7670..08dfb89 100644
--- a/drivers/mtd/devices/ms02-nv.c
+++ b/drivers/mtd/devices/ms02-nv.c
@@ -225,6 +225,7 @@
 	mtd->owner = THIS_MODULE;
 	mtd->read = ms02nv_read;
 	mtd->write = ms02nv_write;
+	mtd->writesize = 1;
 
 	ret = -EIO;
 	if (add_mtd_device(mtd)) {