dt-bindings: serial: Add a new compatible string for UMS9620

The UMS9620 also uses the same serial device with SC9836.
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lore.kernel.org/r/20231215085630.984892-4-chunyan.zhang@unisoc.comAcked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/sprd-uart.yaml

@@ -20,6 +20,7 @@ properties:
               - sprd,sc9860-uart
               - sprd,sc9863a-uart
               - sprd,ums512-uart
+              - sprd,ums9620-uart
           - const: sprd,sc9836-uart
       - const: sprd,sc9836-uart