[oe] rename files dirs

[Dr. Michael Lauer]

> Currently lots of our patches reside in a directory called files.
> Somewhere in the past koen explained me that that is not really proper
> (and I agree with them).

I disagree with that. In fact I'd rather suggest the other way, which
is: Put them all into files/ unless you have a compelling reason not to,
i.e. the moment one patch does not apply any longer to all versions of
the recipes; then it should be moved to PN-PV directory.

Cheers,

:M: