Merge patch series "mkimage: validate default configuration reference"

Merge patch series "mkimage: validate default configuration reference"

Aristo Chen <jj251510319013@gmail.com> says:

This patch series introduces a validation step in `mkimage` to ensure that
the `default` property under the `/configurations` node in a FIT image
references a valid subnode. If the referenced node does not exist, mkimage
now prints an error and fails early. This helps prevent runtime failures
when U-Boot attempts to boot using an undefined configuration.

The first patch implements the validation logic in `fit_image.c`. The second
patch fixes an invalid default configuration reference exposed by this new
check in the `k3-am65-iot2050-boot-image.dtsi`. The final patch adds a test
case to verify that mkimage correctly fails when an invalid default
configuration is present in the ITS file.

This series improves the robustness of FIT image generation and helps
catch malformed image trees during build time.

Link: https://lore.kernel.org/r/20250715130317.3886-1-aristo.chen@canonical.com