[coreboot] k8 and memory training

[ron minnich]

see http://coreboot.pastebin.com/m354e6401

I can't really tell if it's working.

I think there is a bug in simnow spd values. Computed size of the
dimms from spd data is correct. The byte at 31 in SPD claims we only
have 128 MB of RAM, which is wrong. It is right for one DIMM module,
but we have two; it's a factor of two off.

So I've made it a warning, not an error, if spd byte 31 and computed
size don't agree.

ron