Let's use PCIExpressHost with QOM.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Acked-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NJason Baron <jbaron@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>