virtio: console: add locks around buffer removal in port unplug path

{

	struct port_buffer *buf;

	spin_lock_irq(&port->inbuf_lock);

	/* Remove unused data this port might have received. */

	discard_port_data(port);

	reclaim_consumed_buffers(port);

	/* Remove buffers we queued up for the Host to send us data in. */

	while ((buf = virtqueue_detach_unused_buf(port->in_vq)))

		free_buf(buf, true);

	spin_unlock_irq(&port->inbuf_lock);

	spin_lock_irq(&port->outvq_lock);

	reclaim_consumed_buffers(port);

	/* Free pending buffers from the out-queue. */

	while ((buf = virtqueue_detach_unused_buf(port->out_vq)))

		free_buf(buf, true);

	spin_unlock_irq(&port->outvq_lock);

}

/*