virtio_net: introduce ability to get reply info from device

As the spec https://github.com/oasis-tcs/virtio-spec/commit/42f389989823039724f95bbbd243291ab0064f82



Based on the description provided in the above specification, we have
enabled the virtio-net driver to support acquiring some response
information from the device via the CVQ (Control Virtqueue).

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>