net llc: Don't use sysctl tables with .child entries.

The sysctl core no longer natively understands sysctl tables with .child
entries.

Kill the intermediate tables and use register_net_sysctl directly to
remove the need for compatibility code.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>