hwmon: (ds620) Fix overflows seen when writing temperature limits

hwmon: (ds620) Fix overflows seen when writing temperature limits

commit e36ce99ee0815d7919a7b589bfb66f3de50b6bc7 upstream.

Module test reports:

temp1_max: Suspected overflow: [160000 vs. 0]
temp1_min: Suspected overflow: [160000 vs. 0]

This is seen because the values passed when writing temperature limits
are unbound.

Reviewed-by: Jean Delvare <jdelvare@suse.de>
Fixes: 6099469805c2 ("hwmon: Support for Dallas Semiconductor DS620")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>