afs: Apply VLRU safety check for Linux too

This invariant should apply to all platforms, not just those with
dynamic vcaches. Since this prevents an infinite loop if the list os
corrupt or something, having this around everywhere seems useful. So,
drop the check for afsd_dynamic_vcaches.

Reviewed-on: http://gerrit.openafs.org/8555
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit 696db8667d12b1c5639515840f69c9a46d2b866d)

Change-Id: I81e4c7c7678a9f4a3e02952e243735d59b3af35c
Reviewed-on: http://gerrit.openafs.org/9502
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>