sctp: add support for generating stream reconf resp chunk

This patch is to define Re-configuration Response Parameter described
in rfc6525 section 4.4. As optional fields are only for SSN/TSN Reset
Request Parameter, it uses another function to make that.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>