hwmon: (emc1403) fix inverted store_hyst()

Attempts to set the hysteresis value to a temperature below the target
limit fails with "write error: Numerical result out of range" due to
an inverted comparison.

Signed-off-by: Josef Gajdusek <atx@atx.name>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Cc: stable@vger.kernel.org
[Guenter Roeck: Updated headline and description]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>