hwmon: (adt7475) Fix build warning

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

drivers/hwmon/adt7475.c:171:34: warning:
	‘adt7475_of_match’ defined but not used

Mark adt7475_of_match as __maybe_unused to fix the problem.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/adt7475.c

@@ -168,7 +168,7 @@ static const struct i2c_device_id adt7475_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, adt7475_id);
 
-static const struct of_device_id adt7475_of_match[] = {
+static const struct of_device_id __maybe_unused adt7475_of_match[] = {
 	{
 		.compatible = "adi,adt7473",
 		.data = (void *)adt7473