[coreboot] Patching Config.lb

[Myles Watson]

Jordan,

What benefit do we get from patching Config.lb instead of just copying a new
one into the directory?  It seems like the same thing, only the complete
Config.lb would be more human readable.

I just thought that as long as you are regenerating those patches, we might
want to reconsider how we do it.

One of the implications is that now if you switch payloads in buildrom,
Coreboot needs to be unpacked again, because the patch won't apply.  If we
used a new Config.lb, we could just copy over it and run buildtarget again.

Myles