mtd: nand: pxa3xx: Make of_device_id array const

Make of_device_id array const, because all OF functions
handle it as const.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Acked-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/nand/pxa3xx_nand.c

@@ -337,7 +337,7 @@ static struct nand_ecclayout ecc_layout_4KB_bch8bit = {
 /* convert nano-seconds to nand flash controller clock cycles */
 #define ns2cycle(ns, clk)	(int)((ns) * (clk / 1000000) / 1000)
 
-static struct of_device_id pxa3xx_nand_dt_ids[] = {
+static const struct of_device_id pxa3xx_nand_dt_ids[] = {
 	{
 		.compatible = "marvell,pxa3xx-nand",
 		.data       = (void *)PXA3XX_NAND_VARIANT_PXA,