virtio: use err label in __vring_new_virtqueue()

Using error label for unwind in __vring_new_virtqueue. This is useful
for future refacotring.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210604055350.58753-7-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio_ring.c

@@ -2161,10 +2161,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
 
 	vq->split.desc_state = kmalloc_array(vring.num,
 			sizeof(struct vring_desc_state_split), GFP_KERNEL);
-	if (!vq->split.desc_state) {
-		kfree(vq);
-		return NULL;
-	}
+	if (!vq->split.desc_state)
+		goto err_state;
 
 	/* Put everything in free lists. */
 	vq->free_head = 0;
@@ -2175,6 +2173,10 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
 
 	list_add_tail(&vq->vq.list, &vdev->vqs);
 	return &vq->vq;
+
+err_state:
+	kfree(vq);
+	return NULL;
 }
 EXPORT_SYMBOL_GPL(__vring_new_virtqueue);