hwmon: (jc42) Simplify hysteresis mask

Define JC42_CFG_HYST_MASK as the mask _before_ shifting instead of
after shifting. This simplifies the current code slightly, and will
simplify the code to come even more.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>