[SOCK]: Drop inuse pcounter from struct proto (v2).

An uppercut - do not use the pcounter on struct proto.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>