portOutputRegister and portInputRegister are useless

Ok sorry I just realised now that alvesjc allready reported the same.

Yes you should check it, but I think for keeping compatibility with most of the code out there since for normal Arduinos the macros get someting that can be used straight without the need of further comands and that should be good with users thinking that doesn't work as there is nothing documented anyware related this specifc cases.