sctp: do not inherit ipv6_{mc|ac|fl}_list from parent

SCTP needs fixes similar to 83eaddab ("ipv6/dccp: do not inherit
ipv6_mc_list from parent"), otherwise bad things can happen.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>