[MTD] assume mtd->writesize is 1 for NOR flashes

Signed-off-by: Artem B. Bityitskiy
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 04e65d5..a846614 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -465,6 +465,7 @@
 		flash->mtd.name = spi->dev.bus_id;
 
 	flash->mtd.type = MTD_NORFLASH;
+	flash->mtd.writesize = 1;
 	flash->mtd.flags = MTD_CAP_NORFLASH;
 	flash->mtd.size = info->sector_size * info->n_sectors;
 	flash->mtd.erasesize = info->sector_size;