Add an option to install grub2 support tools to the target.
In the context of Buildroot, some useful target tools provided are
grub2-editenv, grub2-reboot, which provide means to manage the grub2,
environment, boot order, and others.
Signed-off-by: Erico Nunes <nunes.erico@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>