dt-bindings: pinctrl: qcom,pmic-gpio: add PM8226 constraints

Document the constraints (number of GPIOs) for PM8226 variant.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220726115202.99108-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>