net: Convert sysctl creating and destroying pernet_operations

These pernet_operations create and destroy sysctl tables,
and they are able to be executed in parallel with any others:

ip_vs_lblc_ops
ip_vs_lblcr_ops

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>