[U-Boot] LL TEMAC V4 refactored

[Stephan Linz]

Back to the discussion from August I have refactored the LL TEMAC
driver. Just in version V4 it is ready to next review.

Note: To use the driver on Microblaze, you will need additional
platform patches by Michal Simek:
  - http://patchwork.ozlabs.org/patch/112535/
  - http://patchwork.ozlabs.org/patch/112534/
  - http://patchwork.ozlabs.org/patch/112532/

I will collect all related patches on a public bundle:
  - http://patchwork.ozlabs.org/user/bundle/2339/


br,
Stephan Linz