The compatibles should include the SoM compatible, this board is based
on the Ka-Ro TX8P-ML81 SoM, so add it to allow using shared code in the
bootloader which uses upstream Linux devicetrees as a base.
Also add the hardware revision to the board compatible to handle
revision specific quirks in the bootloader/userspace.
This is a breaking change, but it is early enough that it can be
corrected without causing any issues.