dt-bindings: arm: qcom: Document the HDK8550 board

Document the Qualcomm SM8550 based HDK (Hardware Development Kit)
embedded development platform designed by Qualcomm and sold by Lantronix.

[1] https://www.lantronix.com/products/snapdragon-8-gen-2-mobile-hardware-development-kit/Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20240125-topic-sm8550-upstream-hdk8550-v3-1-73bb5ef11cf8@linaro.orgSigned-off-by: Bjorn Andersson <andersson@kernel.org>

Documentation/devicetree/bindings/arm/qcom.yaml

@@ -1035,6 +1035,7 @@ properties:
 
       - items:
           - enum:
+              - qcom,sm8550-hdk
               - qcom,sm8550-mtp
               - qcom,sm8550-qrd
           - const: qcom,sm8550