[MTD] Initialize 'writesize'

Signed-off-by: Artem B. Bityutskiy <dedekind@infradead.org>
diff --git a/drivers/mtd/devices/mtd_dataflash.c b/drivers/mtd/devices/mtd_dataflash.c
index a19480d..04271d0 100644
--- a/drivers/mtd/devices/mtd_dataflash.c
+++ b/drivers/mtd/devices/mtd_dataflash.c
@@ -478,6 +478,7 @@
 	device->name = (pdata && pdata->name) ? pdata->name : priv->name;
 	device->size = nr_pages * pagesize;
 	device->erasesize = pagesize;
+	device->writesize = pagesize;
 	device->owner = THIS_MODULE;
 	device->type = MTD_DATAFLASH;
 	device->flags = MTD_CAP_NORFLASH;