[NETFILTER] ctnetlink: add one nesting level for TCP state
To keep consistency, the TCP private protocol information is nested
attributes under CTA_PROTOINFO_TCP. This way the sequence of attributes to
access the TCP state information looks like here below:
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Harald Welte <laforge@netfilter.org> Signed-off-by: David S. Miller <davem@davemloft.net>