dt-bindings: net: mscc-miim: add clock and clock-frequency

Add the (optional) clock input of the MDIO controller and indicate that
the common clock-frequency property is supported. The driver can use it
to set the desired MDIO bus frequency.
Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/mscc,miim.yaml

@@ -33,6 +33,11 @@ properties:
   interrupts:
     maxItems: 1
 
+  clocks:
+    maxItems: 1
+
+  clock-frequency: true
+
 required:
   - compatible
   - reg