dt-bindings: firmware: arm,scmi: drop unneeded quotes and use absolute /schemas path

Cleanup bindings dropping unneeded quotes. Once all these are fixed,
checking for this can be enabled in yamllint.  Also absolute path
starting with /schemas is preferred.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230609140749.65102-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/firmware/arm,scmi.yaml

@@ -214,7 +214,7 @@ properties:
         patternProperties:
           '^regulator@[0-9a-f]+$':
             type: object
-            $ref: "../regulator/regulator.yaml#"
+            $ref: /schemas/regulator/regulator.yaml#
             unevaluatedProperties: false
 
             properties: