hwmon: (hih6130) Fix build warning

If CONFIG_OF is not enabled, the following build warning is observed.

drivers/hwmon/hih6130.c:255:34: warning:
	‘hih6130_of_match’ defined but not used

Mark hih6130_of_match as __maybe_unused to fix the problem.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/hih6130.c

@@ -252,7 +252,7 @@ static const struct i2c_device_id hih6130_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, hih6130_id);
 
-static const struct of_device_id hih6130_of_match[] = {
+static const struct of_device_id __maybe_unused hih6130_of_match[] = {
 	{ .compatible = "honeywell,hih6130", },
 	{ }
 };