net: clean leftover of COMPAT_NET_DEV_OPS removal

COMPAT_NET_DEV_OPS was removed a while back and with it the definition of
netdev_resync_ops() went away. Let's finish the clean-up.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>