[coreboot] SIS device support

[Gregg Levine]

Hello!
I've just been given an SIS based system. I'll know more about it when
I get back from vacation, but is this older family supported on
Coreboot? Or do I need to go back to either of the two original
LinuxBIOS trees I've got someplace?

Basically its the original family that I distinctly remember being
discussed on the original LinuxBIOS list.