mtd: constify of_device_id array

of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/nand/mpc5121_nfc.c

@@ -837,7 +837,7 @@ static int mpc5121_nfc_remove(struct platform_device *op)
 	return 0;
 }
 
-static struct of_device_id mpc5121_nfc_match[] = {
+static const struct of_device_id mpc5121_nfc_match[] = {
 	{ .compatible = "fsl,mpc5121-nfc", },
 	{},
 };