hwmon: (nct6775) Set weight source to zero correctly

This is dead code because j can never be 1 at this point.  We had
intended to just test if the bit was clear.

Fixes: bbd8decd ("hwmon: (nct6775) Add support for weighted fan control")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>