Merge branch 'sctp-fully-support-for-dscp-and-flowlabel-per-transport'

Xin Long says:

====================
sctp: fully support for dscp and flowlabel per transport

Now dscp and flowlabel are set from sock when sending the packets,
but being multi-homing, sctp also supports for dscp and flowlabel
per transport, which is described in section 8.1.12 in RFC6458.

v1->v2:
  - define ip_queue_xmit as inline in net/ip.h, instead of exporting
    it in Patch 1/5 according to David's suggestion.
  - fix the param len check in sctp_s/getsockopt_peer_addr_params()
    in Patch 3/5 to guarantee that an old app built with old kernel
    headers could work on the newer kernel per Marcelo's point.
====================

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