bug#57070: [PATCH] bootloader: extlinux: support for optional FDTDIR

[Mathieu Othacehe]

Hello Reza,

> * gnu/bootloader.scm (<bootloader-configuration>)[device-tree-support?]: new 
> field.
> * gnu/bootloader/extlinux.scm (extlinux-configuration-file): add FDTDIR line
> based on <device-tree-support?> field of <bootloader-configuration>.
> * doc/guix.texi (Bootloader Configuration)[device-tree-support?]: Add
> documentation for the new field.

I pushed this patch with a few modifications.

Thanks,

Mathieu