Revert "virtio-net: enable virtio 1.0"

This reverts commit df91055.

This is because:
- vhost support virtio 1.0 now
- transport code (e.g virtio-pci) set this feature when modern is
  enabled, setting this unconditionally will break disable-modern=on.

Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/net/virtio-net.c

@@ -466,7 +466,6 @@ static uint64_t virtio_net_get_features(VirtIODevice *vdev, uint64_t features)
     }
 
     if (!get_vhost_net(nc->peer)) {
-        virtio_add_feature(&features, VIRTIO_F_VERSION_1);
         return features;
     }
     return vhost_net_get_features(get_vhost_net(nc->peer), features);