The attribute 0 is never used in drbd, so let's use it as pad attribute
in netlink messages. This minimizes the patch.

Note that this patch is only compile-tested.
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>