Add qgraph nodes for virtio-net-pci and virtio-net-device.
Both nodes produce virtio-net, but virtio-net-pci receives
a pci-bus and overrides virtio-pci QOSGraphObject and its functions,
while virtio-net-device receives a virtio and implements
its own functions
Signed-off-by: Emanuele Giuseppe Esposito <e.emanuelegiuseppe@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
