CI: Exclude devicetree-rebasing subtree for CONFIG checks

CI: Exclude devicetree-rebasing subtree for CONFIG checks

Since devicetree-rebasing is an external repo with its own coding style,
exclude it from Azure and gitlab CI CONFIG checks.

Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>