Merge branch 'l2tp-remove-unused-session-fields'

Guillaume Nault says:

====================
l2tp: remove unused session fields

Several fields of the session structures can be set, but remain unused
otherwise.

This series removes these fields and explicitely ignores the
associated ioctls and netlink attributes.
====================

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