[coreboot] legacybios tests on simnow and real hardware

[Myles Watson]

This is what's needed to add legacybios to buildrom.

I've tried legacybios as a payload for v3 qemu and v2 qemu, tyan
s2892, and amd serengeti_cheetah.

It works for v3 qemu and v2 qemu, but not tyan s2892 or amd serengeti_cheetah.

I don't get any serial output from legacybios on any platform, even
though I enable it.

Any ideas?

Thanks,
Myles