net: get rid of multiple bond-related netdevice->priv_flags

Now when bond-related code is moved from net/core/dev.c into bonding
code, multiple priv_flags are not needed anymore. So let them rot.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Reviewed-by: Nicolas de Pesloüan <nicolas.2p.debian@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>