dt-bindings: iio: semtech,sx9324: reference common schema for label

Reference iio.yaml schema from dtschema to allow already used
label property:

  sc7180-trogdor-pazquel360-lte.dtb: proximity@28: 'label' does not match any of the regexes: 'pinctrl-[0-9]+'

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230617103658.114453-2-krzysztof.kozlowski@linaro.org


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>