In their infinite wisdom, the inventors of SCTP designed an API (the
sockets API described in RFC6458), where some members are in host byte
order (like the stream identifier), while other members are in network
byte order (like the PPID).
Let's handle this properly (we assumed both are network byte order), and
also use 16-bit htons/ntohs fo the PPID, rather than htonl/ntohl.
Change-Id: I777174ca2915c6de0063db41a745c71b4a09bbec