hwmon: (nct6775) Enable IO mapping for NCT6797D and NCT6798D

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>