script for custom uboot creation to support Odroid HC4

[phillxnet]

Forum member aquada has expressed interest in testing his HC4 for Rockstor compatibility. @mcbridematt has offered key insights into how we might enable booting on this and related hardware. Essentially a signed uboot instance with accompanying firmware files is required and there are potentially licencing concerns regarding our re-distribution of the tools and resulting firmware files. But we could still begin with offering a script to build a uboot sdcard image that could in turn be used to boot our regular ARM64EFI image on a USB device. At least this is the proposed first step.

Once we have a proven uboot and firmware file set we might move to having a proper profile for this, akin to rou existing Pi4 profile. But distribution of any resulting installer images would depend on the legal position regarding the tools used and associated firmware.

See the following forum thread for details:
https://forum.rockstor.com/t/supported-hardware/8384

Noteworthy links copped from that thread for convenience:
https://wiki.odroid.com/odroid-hc4/software/building_u-boot
https://u-boot.readthedocs.io/en/latest/board/amlogic/odroid-c4.html
with the latter link in turn referencing pre-generated FIP (Firmware Image Package) file sets.
Also note the following upstream reference:
https://github.com/LibreELEC/amlogic-boot-fip

[phillxnet]

Note from the open source tools available here:
https://github.com/LibreELEC/amlogic-boot-fip#readme
It is thought that our target HC4 is of the type: G12A
Reference:
"https://github.com/angerman/meson64-tools (developed for G12B, should work on G12A & SM1)"