dt-bindings: soc: qcom: smd: reference SMD edge schema

The child node of smd is an SMD edge representing remote subsystem.
Bring back missing reference from previously sent patch (disappeared
when applying).

Link: https://lore.kernel.org/r/20220517070113.18023-9-krzysztof.kozlowski@linaro.org
Fixes: 385fad13 ("dt-bindings: remoteproc: qcom,smd-edge: define re-usable schema for smd-edge")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220723082358.39544-1-krzysztof.kozlowski@linaro.org

Documentation/devicetree/bindings/soc/qcom/qcom,smd.yaml

@@ -21,7 +21,7 @@ properties:
 
 patternProperties:
   "^.*-edge|rpm$":
-    type: object
+    $ref: /schemas/remoteproc/qcom,smd-edge.yaml#
     description:
       Each subnode of the SMD node represents a remote subsystem or a remote
       processor of some sort - or in SMD language an "edge". The name of the