dt-bindings: arm: Add bindings for Unisoc SC9863A

Added bindings for Unisoc SC9863A board and SC9863A SoC.
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/sprd.yaml

@@ -25,5 +25,9 @@ properties:
           - enum:
               - sprd,sp9860g-1h10
           - const: sprd,sc9860
+      - items:
+          - enum:
+              - sprd,sp9863a-1h10
+          - const: sprd,sc9863a
 
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