caif_virtio: use simplified virtqueue accessors.

We never add buffers with input and output parts, so use the new accessors.

Cc: Sjur Brendeland <sjur.brandeland@stericsson.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/net/caif/caif_virtio.c

@@ -572,8 +572,7 @@ static int cfv_netdev_tx(struct sk_buff *skb, struct net_device *netdev)
 		goto err;
 	}
 
-	ret = virtqueue_add_buf(cfv->vq_tx, &sg, 1, 0,
-				buf_info, GFP_ATOMIC);
+	ret = virtqueue_add_outbuf(cfv->vq_tx, &sg, 1, buf_info, GFP_ATOMIC);
 	if (unlikely((ret < 0))) {
 		/* If flow control works, this shouldn't happen */
 		netdev_warn(cfv->ndev, "Failed adding buffer to TX vring:%d\n",