Migration: Add i82801b11 migration data

The i82801b11 bridge didn't have a vmsd and thus didn't send
any migration data, including that of its parent PCIBridge object.
The symptom being if the guest used any devices behind the bridge
the guest crashed (mostly with various interrupt related issues).

Note: This will cause migration from old qemus that used this device to
explicitly fail during migration as opposed to the guest crashing.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Suggested-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
