sctp: fix error path in sctp_proc_init

After the sctp_remaddr_proc_init failed, the proper rollback is
not the sctp_remaddr_proc_exit, but the sctp_assocs_proc_exit.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>