checkpatch.pl: Report an error for CONFIG_xPL_BUILD in device trees

The defines for the different build phases shouldn't be used in device
trees, currently they aren't even defined for device tree pre processing,
resulting in build errors.

Link: https://lists.denx.de/pipermail/u-boot/2025-March/582787.html
Signed-off-by: Hendrik Donner <hd@os-cillation.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed