Backport v2024 <- v2025pre: Adapt to new version of RPi4 U-boot

Backport !647 (merged)

The U-boot version in LAVA for RPi4 has been updated to 2024.01+dfsg-1+apertis7bv2025dev3b1 which supports a new layout for RPi4 to allow larger kernels to be used.

The previous U-boot version in LAVA for RPi4 was 2021.10+dfsg-1+apertis10bv2022.1b3 which had different default environment, witch supported distro_boot as command.

By default Apertis relied in distro_boot which was the standard way of booting distributions in previous U-boot version. With the new version U-boot the boot command needs to be adapted to use bootflow

https://docs.u-boot.org/en/stable/develop/bootstd.html

Signed-off-by: Walter Lozano walter.lozano@collabora.com