dt-bindings: pinctrl: qcom,pmic-gpio: document PMC8180 and PMC8180C

Document qcom,pmc8180-gpio and qcom,pmc8180c-gpio compatibles already
used in DTS and in the same binding in allOf:if:then section for
narrowing available GPIOs:

  sc8180x-primus.dtb: pmic@4: gpio@c000:compatible:0: 'qcom,pmc8180c-gpio' is not one of ...

Fixes: 04bed640 ("dt-bindings: pinctrl: qcom,pmic-gpio: describe gpio-line-names")
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230720083539.73675-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>