hwmon: (w83627ehf) Unify temperature register access, and use strict string conversions

This patch unifies temperature register access, and replaces simple_strtoXXX
with strict_strtoXXX throughout the driver.
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Ian Dobson <i.dobson@planet-ian.com>