hwmon: Allow writing of negative trigger temperatures

- replace differing temperature variable types by long
- use strtol() instead of strtoul() for conversion

Signed-off-by: Christian Hohnstaedt <chohnstaedt@innominate.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>

drivers/hwmon/ds1621.c

@@ -151,7 +151,7 @@ static ssize_t set_temp(struct device *dev, struct device_attribute *da,
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ds1621_data *data = ds1621_update_client(dev);
-	u16 val = LM75_TEMP_TO_REG(simple_strtoul(buf, NULL, 10));
+	u16 val = LM75_TEMP_TO_REG(simple_strtol(buf, NULL, 10));
 
 	mutex_lock(&data->update_lock);
 	data->temp[attr->index] = val;