FROMLIST: bpf: Remove duplicate tcp_filter hook in ipv6

FROMLIST: bpf: Remove duplicate tcp_filter hook in ipv6

There are two tcp_filter hooks in tcp_ipv6 ingress path currently.
One is at tcp_v6_rcv and another is in tcp_v6_do_rcv. It seems the
tcp_filter() call inside tcp_v6_do_rcv is redundent and some packet
will be filtered twice in this situation. This will cause trouble
when using eBPF filters to account traffic data.

Signed-off-by: Chenbo Feng <fengc@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(url: http://patchwork.ozlabs.org/patch/774126/)
Bug: 30950746
Change-Id: Id4fe8cd5b7bac11a4d4141e203dd4b9fa59f3d6c