dt-bindings: mfd: ti,j721e-system-controller: Add SoC chip ID

The system-controller node also contains the chip-id node that is used
to identify the SoC specific properties. Add a pattern property to
match to the same, and add to the example.

Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230418010019.1222431-1-nm@ti.com

Documentation/devicetree/bindings/mfd/ti,j721e-system-controller.yaml

@@ -62,6 +62,12 @@ patternProperties:
     description:
       The phy node corresponding to the ethernet MAC.
 
+  "^chipid@[0-9a-f]+$":
+    type: object
+    $ref: /schemas/hwinfo/ti,k3-socinfo.yaml#
+    description:
+      The node corresponding to SoC chip identification.
+
 required:
   - compatible
   - reg
@@ -99,5 +105,10 @@ examples:
             reg = <0x4140 0x18>;
             #clock-cells = <1>;
         };
+
+        chipid@14 {
+            compatible = "ti,am654-chipid";
+            reg = <0x14 0x4>;
+        };
     };
 ...