As new_device and destroy_device use an int instead of a
"struct virtio_net *", The comment about setting VIRTIO_DEV_RUNNING
doesn't make sense anymore, plus If I've correctly understand the
code, the drivers take care of setting the flag before calling the
callbacks, so I guess that this comment is obsolet and I've remove it.
Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com> Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>