Merge branch 'sctp-stream-schedulers'

Marcelo Ricardo Leitner says:

====================
Introduce SCTP Stream Schedulers

This patchset introduces the SCTP Stream Schedulers are defined by
https://tools.ietf.org/html/draft-ietf-tsvwg-sctp-ndata-13

It provides 3 schedulers at the moment: FCFS, Priority and Round Robin.
The other 3, Round Robin per packet, Fair Capacity and Weighted Fair
Capacity will be added later. More specifically, WFQ is required by
WebRTC Datachannels.

The draft also defines the idata chunk, allowing a usermsg to be
interrupted by another piece of idata from another stream. This patchset
*doesn't* include it. It will be posted later by Xin Long.  Its
integration with this patchset is very simple and it basically only
requires a tweak in sctp_sched_dequeue_done(), to ignore datamsg
boundaries.

The first 5 patches are a preparation for the next ones. The most
relevant patches are the 4th and 6th ones. More details are available on
each patch.

v2: changelog update on patch 3
====================

Signed-off-by: David S. Miller <davem@davemloft.net>