dt-bindings: leds: lp55xx: allow label

The Linux driver and at least one upstream board use 'label' property:

  qcom/msm8996-xiaomi-gemini.dtb: lp5562@30: 'label' does not match any of the regexes: '^led@[0-8]$', '^multi-led@[0-8]$', 'pinctrl-[0-9]+'

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221127204058.57111-3-krzysztof.kozlowski@linaro.org


Signed-off-by: Rob Herring <robh@kernel.org>