Ability to set battery thresholds from coreboot config-tool payload about skulls

[Thrilleratplay]

@gazny If you are a Linux user, I have heard that the v4.17 kernel will be have this threshold patch.

Personally, this is a setting I would prefer to change in the user space for times those I want to have a full charge if I plan on using my battery for a period of time.

[merge]

I think this would be a nvramcui development issue, but I doubt writing EC registers is in their scope either. I think the best fit would be to write a Linux driver for the x230's battery platform driver's sysfs interface.

[gazny]

I havnt seen many things on battery threshold intergation for corebooted x230s. The 4.17 kernnel hopfully will be sufficient.