arm: dts: Add k3-j721e-beagleboneai64

arm: dts: Add k3-j721e-beagleboneai64

BeagleBoard.org BeagleBone AI-64 is an open source hardware single
board computer based on the Texas Instruments TDA4VM SoC featuring
dual-core 2.0GHz Arm Cortex-A72 processor, C7x+MMA and 2 C66x
floating-point VLIW DSPs, 3x dual ARM Cortex-R5 co-processors,
2x 6-core Programmable Real-Time Unit and Industrial Communication
SubSystem, PowerVR Rogue 8XE GE8430 3D GPU. The board features 4GB
DDR4, USB3.0 Type-C, 2x USB SS Type-A, miniDisplayPort, 2x 4-lane
CSI, DSI, 16GB eMMC flash, 1G Ethernet, M.2 E-key for WiFi/BT, and
BeagleBone expansion headers.

This board family can be indentified by the BBONEAI-64-B0 in the
at24 eeprom:

[aa 55 33 ee 01 37 00 10  2e 00 42 42 4f 4e 45 41 |.U3..7....BBONEA|]
[49 2d 36 34 2d 42 30 2d  00 00 42 30 30 30 37 38 |I-64-B0-..B00078|]

Baseline of the devicetree is from v6.6-rc1

https://beagleboard.org/ai-64
https://git.beagleboard.org/beagleboard/beaglebone-ai-64

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
Signed-off-by: Nishanth Menon <nm@ti.com>