tools/virtio: Use __vring_new_virtqueue in virtio_test.c

As updated in ("2a2d1382

 virtio: Add improved queue allocation API")

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Link: https://lore.kernel.org/r/20200418102217.32327-6-eperezma@redhat.com


Signed-off-by: Michael S. Tsirkin <mst@redhat.com>