dt-bindings: net: micrel,ks8851: allow SPI device properties

The Micrel KS8851 can be attached to SPI or parallel bus and the
difference is expressed in compatibles.  Allow common SPI properties
when this is a SPI variant and narrow the parallel memory bus properties
to the second case.

This fixes dtbs_check warning:

  qcom-msm8960-cdp.dtb: ethernet@0: Unevaluated properties are not allowed ('spi-max-frequency' was unexpected)
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230619170134.65395-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/micrel,ks8851.yaml

@@ -44,13 +44,13 @@ required:
 
 allOf:
   - $ref: ethernet-controller.yaml#
-  - $ref: /schemas/memory-controllers/mc-peripheral-props.yaml#
   - if:
       properties:
         compatible:
           contains:
             const: micrel,ks8851
     then:
+      $ref: /schemas/spi/spi-peripheral-props.yaml#
       properties:
         reg:
           maxItems: 1
@@ -60,6 +60,7 @@ allOf:
           contains:
             const: micrel,ks8851-mll
     then:
+      $ref: /schemas/memory-controllers/mc-peripheral-props.yaml#
       properties:
         reg:
           minItems: 2