linux: exclude from hash check except for latest version

linux: exclude from hash check except for latest version

We don't have a hash for any linux version. We currently also don't
have a hash for the latest version, but if we ever add a hash, it
will only be for the latest version.

This simplifies the code a little because soon we will add hash checks
for git as well, so we also need an exclusion in that case. It's much
easier to always exclude except in the single case where we do have a
hash.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>