vdpa: Fix index calculus at vhost_vdpa_svqs_start

With the introduction of MQ the index of the vq needs to be calculated
with the device model vq_index.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220512175747.142058-5-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/vhost-vdpa.c

@@ -1018,7 +1018,7 @@ static bool vhost_vdpa_svqs_start(struct vhost_dev *dev)
         VirtQueue *vq = virtio_get_queue(dev->vdev, dev->vq_index + i);
         VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, i);
         struct vhost_vring_addr addr = {
-            .index = i,
+            .index = dev->vq_index + i,
         };
         int r;
         bool ok = vhost_vdpa_svq_setup(dev, svq, i, &err);