arm: dts: Add initial support for J721S2 SoC

arm: dts: Add initial support for J721S2 SoC

The J721S2 SoC belongs to the K3 Multicore SoC architecture platform,
providing advanced system integration in automotive ADAS applications and
industrial applications requiring AI at the network edge. This SoC extends
the Jacinto 7 family of SoCs with focus on lowering system costs and power
while providing interfaces, memory architecture and compute performance for
single and multi-sensor applications.

Some highlights of this SoC are:

* Dual Cortex-A72s in a single cluster, three clusters of lockstep capable
dual Cortex-R5F MCUs, Deep-learning Matrix Multiply Accelerator(MMA), C7x
floating point Vector DSP.
* 3D GPU: Automotive grade IMG BXS-4-64
* Vision Processing Accelerator (VPAC) with image signal processor and
Depth and Motion Processing Accelerator (DMPAC)
* Two CSI2.0 4L RX plus one eDP/DP, two DSI Tx, and one DPI interface.
* Two Ethernet ports with RGMII support.
* Single 4 lane PCIe-GEN3 controllers, USB3.0 Dual-role device subsystems,
* Up to 20 MCANs, 5 McASP, eMMC and SD, OSPI/HyperBus memory controller,
QSPI, I3C and I2C, eCAP/eQEP, eHRPWM, MLB among other peripherals.
* Hardware accelerator blocks containing AES/DES/SHA/MD5 called SA2UL
management.

See J721S2 Technical Reference Manual (SPRUJ28 – NOVEMBER 2021)
for further details: http://www.ti.com/lit/pdf/spruj28

Introduce basic support for the J721S2 SoC.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>