Similar to other recent chips from Nuvoton, IO mapping may be disabled
by default. Enable it when instantiating the driver and after resume.

Fixes: 0599682b ("hwmon: (nct6775) Add support for NCT6798D")
Fixes: e41da286 ("hwmon: (nct6775) Add support for NCT6797D")
Reported-by: Michael Cook <mcook@mackal.net>
Cc: Michael Cook <mcook@mackal.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>