watchdog: xilinx: 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>
Reviewed-by: Michal Simek <monstr@monstr.eu>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/of_xilinx_wdt.c

@@ -225,7 +225,7 @@ static int xwdt_remove(struct platform_device *pdev)
 }
 
 /* Match table for of_platform binding */
-static struct of_device_id xwdt_of_match[] = {
+static const struct of_device_id xwdt_of_match[] = {
 	{ .compatible = "xlnx,xps-timebase-wdt-1.00.a", },
 	{ .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
 	{},