armsom rk3588 boards: use radxa's new uboot

[amazingfate]

Description

Use radxa's next-dev-v2024.03 branch for armsom's boards.
Note that I have to remove CONFIG_OPTEE_ALWAYS_USE_SECURITY_PARTITION=y from defconfig to boot the board. So boards affected by #6534 like nanopi6 and nanopc-t6 should also check this.
@efectn @Tonymac32

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also note any relevant details for your test configuration.

• ./compile.sh BOARD=armsom-sige7 BRANCH=vendor BUILD_DESKTOP=no BUILD_MINIMAL=no DEB_COMPRESS=xz KERNEL_CONFIGURE=no RELEASE=bookworm KERNEL_GIT=shallow

Checklist:

Please delete options that are not relevant.

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[efectn]

Unfortunately NanoPi R6 is not near me right now

[igorpecovnik]

R6S will be tested in CI.