ich9: APIs for pc guest info

ich9: APIs for pc guest info

This adds APIs that will be used to fill in
acpi tables, implemented using QOM,
to various ich9 components.
Some information is still missing in QOM,
so we fall back on lookups by type instead.

Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Tested-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>