hwmon: (adt7411) set bit 3 in CFG1 register

According to the datasheet you should only write 1 to this bit. If it is
not set, at least AIN3 will return bad values on newer silicon revisions.

Fixes: d84ca5b3 ("hwmon: Add driver for ADT7411 voltage and temperature sensor")
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>