net: fix sctp breakage

broken by commit 5e739d17; AFAICS should
be -stable fodder as well...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Aced-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>