tools/virtio: Use tools/include/list.h instead of stubs

It should not make any significant difference but reduce stub code.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Link: https://lore.kernel.org/r/20200418102217.32327-9-eperezma@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>