af_key: more info leaks in pfkey messages

[ Upstream commit ff862a4668dd6dba962b1d2d8bd344afa6375683 ]

This is inspired by a5cc68f3d6 "af_key: fix info leaks in notify
messages".  There are some struct members which don't get initialized
and could disclose small amounts of private information.

Acked-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>