dt-bindings: pinctrl: qcom,msm8909-tlmm: do not require function on non-GPIOs

Certain pins, like SDcard related, do not have functions and such should
not be required.
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221016170035.35014-20-krzysztof.kozlowski@linaro.orgSigned-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Documentation/devicetree/bindings/pinctrl/qcom,msm8909-tlmm.yaml

@@ -113,7 +113,6 @@ $defs:
 
     required:
       - pins
-      - function
 
     additionalProperties: false