Merge branch 'sctp-stream-interleave'

Xin Long says:

====================
sctp: Implement Stream Interleave: Interaction with Other SCTP Extensions

Stream Interleave would be implemented in two Parts:

   1. The I-DATA Chunk Supporting User Message Interleaving
   2. Interaction with Other SCTP Extensions

Overview in section 2.3 of RFC8260 for Part 2:

   The usage of the I-DATA chunk might interfere with other SCTP
   extensions.  Future SCTP extensions MUST describe if and how they
   interfere with the usage of I-DATA chunks.  For the SCTP extensions
   already defined when this document was published, the details are
   given in the following subsections.

As the 2nd part of Stream Interleave Implementation, this patchset mostly
adds the support for SCTP Partial Reliability Extension with I-FORWARD-TSN
chunk. Then adjusts stream scheduler and stream reconfig to make them work
properly with I-DATA chunks.

In the last patch, all stream interleave codes will be enabled by adding
sysctl to allow users to use this feature.

v1 -> v2:
  - removed the intl_enable check from sctp_chunk_event_lookup, as Marcelo's
    suggestion.
  - fixed a typo in changelog.
====================

Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>