dt-bindings: phy: cadence-sierra: Add binding to specify SSC mode

Add binding to specify Spread Spectrum Clocking mode used.
Signed-off-by: Swapnil Jakhade <sjakhade@cadence.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211223060137.9252-5-sjakhade@cadence.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/phy-cadence-sierra.yaml

@@ -113,6 +113,15 @@ patternProperties:
         minimum: 1
         maximum: 16
 
+      cdns,ssc-mode:
+        description:
+          Specifies the Spread Spectrum Clocking mode used. It can be NO_SSC,
+          EXTERNAL_SSC or INTERNAL_SSC.
+          Refer include/dt-bindings/phy/phy-cadence.h for the constants to be used.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [0, 1, 2]
+        default: 1
+
     required:
       - reg
       - resets