hwmon: (max6697) fix coccinelle warnings

drivers/hwmon/max6697.c:649:1-3: WARNING: PTR_RET can be used

 Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: coccinelle/api/ptr_ret.cocci

CC: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/max6697.c

@@ -646,10 +646,7 @@ static int max6697_probe(struct i2c_client *client,
 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 							   data,
 							   max6697_groups);
-	if (IS_ERR(hwmon_dev))
-		return PTR_ERR(hwmon_dev);
-
-	return 0;
+	return PTR_ERR_OR_ZERO(hwmon_dev);
 }
 
 static const struct i2c_device_id max6697_id[] = {