arch: arm64: ti: Add support J721S2 Common Processor Board

The EVM architecture for J721S2 is similar to that of J721E and J7200. It
is as follows,

+------------------------------------------------------+
|   +-------------------------------------------+      |
|   |                                           |      |
|   |        Add-on Card 1 Options              |      |
|   |                                           |      |
|   +-------------------------------------------+      |
|                                                      |
|                                                      |
|                     +-------------------+            |
|                     |                   |            |
|                     |   SOM             |            |
|  +--------------+   |                   |            |
|  |              |   |                   |            |
|  |  Add-on      |   +-------------------+            |
|  |  Card 2      |                                    |    Power Supply
|  |  Options     |                                    |    |
|  |              |                                    |    |
|  +--------------+                                    | <---
+------------------------------------------------------+
                                 Common Processor Board

Common Processor board is the baseboard that contains most of the actual
connectors, power supply etc. The System on Module (SoM) is plugged on to
the common processor baord. Therefore, add support for peripherals brought
out in the common processor board.

Common Processor Board: https://www.ti.com/tool/J721EXCPXEVM



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/20211207080904.14324-6-a-govindraju@ti.com