Merge branch 'mptcp-refactor-token-container'

Paolo Abeni says:

====================
mptcp: refactor token container

Currently the msk sockets are stored in a single radix tree, protected by a
global spin_lock. This series moves to an hash table, allocated at boot time,
with per bucker spin_lock - alike inet_hashtables, but using a different key:
the token itself.

The above improves scalability, as write operations will have a far later chance
to compete for lock acquisition, allows lockless lookup, and will allow
easier msk traversing - e.g. for diag interface implementation's sake.

This also introduces trivial, related, kunit tests and move the existing in
kernel's one to kunit.

v1 -> v2:
 - fixed a few extra and sparse warns
====================

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