dt-bindings: spmi: mtk,spmi-mtk-pmif: drop unneeded quotes

Cleanup bindings dropping unneeded quotes. Once all these are fixed,
checking for this can be enabled in yamllint.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230609140655.64529-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/spmi/mtk,spmi-mtk-pmif.yaml

@@ -14,7 +14,7 @@ description: |+
   for multiple SoCs to control a single SPMI master.
 
 allOf:
-  - $ref: "spmi.yaml"
+  - $ref: spmi.yaml
 
 properties:
   compatible: