cpufreq: Loongson2: constify platform_device_id

platform_device_id are not supposed to change at runtime. All functions
working with platform_device_id provided by <linux/platform_device.h>
work with const platform_device_id. So mark the non-const structs as
const.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/loongson2_cpufreq.c

@@ -114,7 +114,7 @@ static struct cpufreq_driver loongson2_cpufreq_driver = {
 	.attr = cpufreq_generic_attr,
 };
 
-static struct platform_device_id platform_device_ids[] = {
+static const struct platform_device_id platform_device_ids[] = {
 	{
 		.name = "loongson2_cpufreq",
 	},