hwmon: (lm92) Prevent overflow problem when writing large limits

hwmon: (lm92) Prevent overflow problem when writing large limits

On platforms with sizeof(int) < sizeof(long), writing a temperature
limit larger than MAXINT will result in unpredictable limit values
written to the chip. Avoid auto-conversion from long to int to fix
the problem.

The hysteresis temperature range depends on the value of
data->temp[attr->index], since val is subtracted from it.
Use a wider clamp, [-120000, 220000] should do to cover the
possible range. Also add missing TEMP_TO_REG() on writes into
cached hysteresis value.

Also uses clamp_val to simplify the code a bit.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
[Guenter Roeck: Fixed double TEMP_TO_REG on hysteresis updates]
Cc: stable@vger.kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>