Add initial support for BeagleBoard PocketBeagle2

[Grippy98]

Hey All,

Let's try this again. Apologies for the last force push, I cleaned it up now so it's a CSC file only.

This PR adds support for the BeagleBoard PocketBeagle 2.
Features, schematics, and purchase links can be found on the board page[0].

Notable features:

• 2x 64-bit Arm-Cortex A53 microprocessor
• 512MB RAM
• On-board ADC via a TI MSPM0L1105 Cortex-M0+ MCU
• Onboard LiPo Battery charger
• JST-SH 1.00mm UART debug port compatible with Pi Debug probe
• Pre-soldered headers compatible with original PocketBeagle

Thanks! and especially many thanks to @glneo for his patience.

[0] https://www.beagleboard.org/boards/pocketbeagle-2

How Has This Been Tested?

Build/Boot tested Bookworm CLI/Minimal on Edge(v6.12) kernel
Build/Boot tested Noble CLI/Minimal on Edge(v6.12) kernel
UART works

Checklist:

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

[Grippy98]

When defining a LINUXFAMILY, it expects a new kernel config so putting it under k3-beagle-edge which is going to be where I keep the source for PB2 and BeagleY (which I'll push next week) instead of calling it k3-pb2.

If you think this approach makes sense I'm good to keep it like this for now. This ultimately needs to be cleaned up once J722s and PB2 are upstreamed.

[rpardini]

defining a LINUXFAMILY, it expects a new kernel config

Yes, indeed, as it sets a whole new kernel package (as intended), and that ofc needs a .config. You could alternatively set LINUXCONFIG to point to the regular k3 config instead of duplicating, if they're the same.