Merge branch 'mptcp-fixes'

Mat Martineau says:

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mptcp: Fix address advertisement races and stabilize tests

Patches 1, 2, and 7 modify two self tests to give consistent, accurate
results by fixing timing issues and accounting for syncookie behavior.

Paches 3-6 fix two races in overlapping address advertisement send and
receive. Associated self tests are updated, including addition of two
MIBs to enable testing and tracking dropped address events.
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Signed-off-by: David S. Miller <davem@davemloft.net>