dt-bindings: net: hirschmann,hellcreek: use absolute path to other schema

Absolute path to other DT schema is preferred over relative one.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Kurt Kanzenbach <kurt@linutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220726115650.100726-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/dsa/hirschmann,hellcreek.yaml

@@ -48,7 +48,7 @@ properties:
       "^led@[01]$":
         type: object
         description: Hellcreek leds
-        $ref: ../../leds/common.yaml#
+        $ref: /schemas/leds/common.yaml#
 
         properties:
           reg: