platform/x86: simatic-ipc: add main driver for Siemens devices

This mainly implements detection of these devices and will allow
secondary drivers to work on such machines.

The identification is DMI-based with a vendor specific way to tell them
apart in a reliable way.

Drivers for LEDs and Watchdogs will follow to make use of that platform
detection.

There is also some code to allow secondary drivers to find GPIO memory,
that needs to be in place because the pinctrl drivers do not come up.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Link: https://lore.kernel.org/r/20211213120502.20661-2-henning.schild@siemens.com


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