[coreboot] More experiments with disabling the ME

[Nicola Corna]

Hi Persmule,

for the ME in the board status repo I used a ME image extracted from a
Chromebook C710 BIOS dump, you can find the same dump somewhere in the
web.
Once we repair our spare X220 we can resume the work on ME and,
hopefully, reduce further the firmware size.

Nicola