The SCTP Quick failover draft [1] section 5.1, point 5 says that the cwnd
should be 1 MTU. So, instead of 1, set it to 1 MTU.

  [1] https://tools.ietf.org/html/draft-nishida-tsvwg-sctp-failover-05Reported-by: NKarl Heiss <kheiss@gmail.com>
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Acked-by: NVlad Yasevich <vyasevich@gmail.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>