hwmon: (lm75) Aproximate sample times to data-sheet values

Current sample time values are over estimated, this patches applies
values closer to the ones defined in the data-sheets.

Signed-off-by: Iker Perez del Palomar Sustatxa <iker.perez@codethink.co.uk>
[groeck: resolved conflicts; use default conversion times]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>