arm: dts: k3-j721e-sk: Add initial A72 specific dts support

J721E Starter Kit (SK)[1] is a low cost, small form factor board designed
for TI’s J721E SoC. TI’s J721E SoC comprises of dual core A72, high
performance vision accelerators, video codec accelerators, latest C71x
and C66x DSP, high bandwidth real-time IPs for capture and display, GPU,
dedicated safety island and security accelerators. The SoC is power
optimized to provide best in class performance for industrial and
automotive applications.

    J721E SK supports the following interfaces:
    * 4 GB LPDDR4 RAM
    * x1 Gigabit Ethernet interface
    * x1 USB 3.0 Type-C port
    * x3 USB 3.0 Type-A ports
    * x1 PCIe M.2 E Key
    * x1 PCIe M.2 M Key
    * 512 Mbit OSPI flash
    * x2 CSI2 Camera interface (RPi and TI Camera connector)
    * 40-pin Raspberry Pi GPIO header

Add A72 specific dts for J721E-SK.

[1] https://www.ti.com/tool/SK-TDA4VM



Signed-off-by: Sinthu Raja <sinthu.raja@ti.com>