$ sudo apt-get update
$ sudo apt-get install grub-coreboot 

grub-coreboot is installed in your system.

Make ensure the grub-coreboot package were installed using the commands given below,

$ sudo dpkg-query -l | grep grub-coreboot *

You will get with grub-coreboot package name, version, architecture and description in a table

grub-coreboot package basic information: