hwmon: (max197) Constify platform_device_id

The platform_device_id is not modified by the driver and core uses it as
const.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
diff --git a/drivers/hwmon/max197.c b/drivers/hwmon/max197.c
index cb0dcfd..07628569 100644
--- a/drivers/hwmon/max197.c
+++ b/drivers/hwmon/max197.c
@@ -324,7 +324,7 @@
 	return 0;
 }
 
-static struct platform_device_id max197_device_ids[] = {
+static const struct platform_device_id max197_device_ids[] = {
 	{ "max197", max197 },
 	{ "max199", max199 },
 	{ }