VIM1S/VIM4: Allow building on arm64 platform

[viraniac]

Description

Add support to build VIM1S/VIM4 images on arm64 platform. Currently only x86_64 platform was supported as build host as the gcc-linaro-aarch64-elf compiler version 7.3.1-2018.05 was not available for aarch64 platform. I have built the compiler myself on vim4 using the commands given here

How Has This Been Tested?

• [X] Compiled u-boot for VIM1S and VIM4
• [X] Created a minimal bookworm image for VIM1S and booted on the same

Checklist:

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

[viraniac]

@igorpecovnik Could you please upload the gcc compiler tarball from my google drive to https://dl.armbian.com/_toolchain. That compiler tarball will be used by the changes of this PR.