platform/x86: dell-ddv: Update ABI documentation

Synchronize the ABI documentation with the driver documentation
and direct users to the latter in case the search for more
detailed information.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20230508204241.11076-2-W_Armin@gmx.de


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