arm64: dts: ti: Add initial support for J721S2 System on Module

A System on Module (SoM) contains the SoC, PMIC, DDR and basic high speed
components necessary for functionality. Therefore, add support for the
components present on the SoM.

SoM: https://www.ti.com/lit/zip/sprr439



Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Kishon Vijay Abraham I <kishon@ti.com>
Link: https://lore.kernel.org/r/20211207080904.14324-5-a-govindraju@ti.com