We are going to introduce a shared vhost user state which
will be named as 'VhostUserState'. So add 'Net' prefix to
the existing internal state structure in the vhost-user
netdev to avoid conflict.

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>