Merge branch 'l2tp-avoid-aliasing-tunnels-socket-pointer'

Guillaume Nault says:

====================
l2tp: avoid aliasing tunnels socket pointer

We don't need to copy the tunnel's socket pointer in the pseudo-wire
specific session structures. This uselessly complicates the code
and hampers evolution.

This series was part of an effort to protect tunnels socket pointer
with RCU. But since it provides nice cleanup, I submit it separately.
====================

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