netfilter: xt_qtaguid: fix bad tcp_time_wait sock handling

Since (41063e9d ipv4: Early TCP socket demux), skb's can have an sk which
is not a struct sock but the smaller struct inet_timewait_sock without an
sk->sk_socket. Now we bypass sk_state == TCP_TIME_WAIT

Signed-off-by: JP Abgrall <jpa@google.com>