[coreboot] EP80579 reference platform

[Myles Watson]

> The problem with Truxton booting in trunk seems to have appeared in the
> migration to the new Makefile system.
>
> If I drop a CONFIG_SSE=y into the .config file using a trunk build I can
> boot!
>
> However, I don't really see how this flag gets set.  Doing a 'grep -RH
> CONFIG_SSE' points to the two makefile includes that add the enable_sse
> code, but no references to setting the flag.

I added it in 5505.  I think we should put an #error in the file that
uses these instructions if CONFIG_SSE isn't set.

Thanks,
Myles