Merge branch 'sk-const'

Guillaume Nault says:

====================
net: Mark the sk parameter of routing functions as 'const'.

The sk_getsecid security hook prevents the use of a const sk pointer in
several routing functions. Since this hook should only read sk data,
make its sk argument const (patch 1), then constify the sk parameter of
various routing functions (patches 2-4).

Build-tested with make allmodconfig.
====================

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