dt-bindings: arm: ti: Add bindings for PHYTEC AM64x based hardware

Add devicetree bindings for AM64x based phyCORE-AM64 SoM
and phyBOARD-Electra RDK.
Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20230104162927.1215033-1-w.egorov@phytec.de

Documentation/devicetree/bindings/arm/ti/k3.yaml

@@ -38,6 +38,12 @@ properties:
               - ti,am642-sk
           - const: ti,am642
 
+      - description: K3 AM642 SoC PHYTEC phyBOARD-Electra
+        items:
+          - const: phytec,am642-phyboard-electra-rdk
+          - const: phytec,am64-phycore-som
+          - const: ti,am642
+
       - description: K3 AM654 SoC
         items:
           - enum: