watchdog: simatic-ipc-wdt: make IO region access of one model muxed

The IO region used for the watchdog also hold CMOS battery monitoring
information. Make the access muxed so that a hwmon driver can use the
region as well.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230706154831.19100-2-henning.schild@siemens.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>