dt-bindings: arm/calxeda: drop unneeded quotes

Drop unneeded quotes over simple string values to fix a soon to be
enabled yamllint warning:

  [error] string value is redundantly quoted with any quotes (quoted-strings)
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231122224432.2809781-1-robh@kernel.orgSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/calxeda/l2ecc.yaml

@@ -16,7 +16,7 @@ maintainers:
 
 properties:
   compatible:
-    const: "calxeda,hb-sregs-l2-ecc"
+    const: calxeda,hb-sregs-l2-ecc
 
   reg:
     maxItems: 1