TEST: Make testcase aware of a kernel behaviour change

This is analogous to the following commit:

	commit 7963a21a183ccc5658acff3a1bf05ec3b0688946
	Author: David Howells <dhowells@redhat.com>
	Date: Wed, 15 Jan 2014 15:07:05 +0000
	Subject: TEST: Make search/valid aware that the behaviour of the kernel changed

The kernel changed referred to also affected timeout/valid, which had
previously been affected by another change. All in all, between 3.8 and 3.12,
kernel returned ENOKEY instead of EKEYEXPIRED.

Signed-off-by: Christian Kastner <ckk@debian.org>
Signed-off-by: David Howells <dhowells@redhat.com>