mfd: sm501: 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>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/sm501.c

@@ -1726,7 +1726,7 @@ static struct pci_driver sm501_pci_driver = {
 
 MODULE_ALIAS("platform:sm501");
 
-static struct of_device_id of_sm501_match_tbl[] = {
+static const struct of_device_id of_sm501_match_tbl[] = {
 	{ .compatible = "smi,sm501", },
 	{ /* end */ }
 };