[U-Boot] V2 implementation of generic distro options

In this set of patches I am adding a generic set of config options for Distros to work with. this enables for simplified support of systems by distros. Fixed in V2 is updating the guard to match the renamed filename since the RFC series.

I have left out any implementations in this set of patches. I am working to redo all the implementations based on the work done by Stephen Warren in his recent set to base on top of these and his exists work.

Dennis