[coreboot] Latest GRUB uses Multiboot on coreboot

[Robert Millan]

Hi!

Starting with revision 1910, latest version of GRUB uses the newly added
Multiboot support in coreboot.  If you're using GRUB on coreboot, when you
update to the latest GRUB mind that you also have to be using a recent
version of coreboot.

The main advantage this provides, is that you can now test how will GRUB
for coreboot work on your hardware without having to flash it, and without
having to worry about "bricking" the board.  E.g. from GRUB 2:

grub> multiboot /grub.elf
  grub> boot

and from GRUB Legacy:

grub> kernel /grub.elf
  grub> boot