Merge branch 'SCTP-PMTU-discovery-fixes'

Marcelo Ricardo Leitner says:

====================
SCTP PMTU discovery fixes

This patchset fixes 2 issues with PMTU discovery that can lead to flood
of retransmissions.
The first patch fixes the issue for when PMTUD is disabled by the
application, while the second fixes it for when its enabled.

Please consider these to stable.
====================

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