dt-bindings: pinctrl: qcom,sc7180: convert to dtschema

dt-bindings: pinctrl: qcom,sc7180: convert to dtschema

Convert Qualcomm SC7180 pin controller bindings to DT schema.  Keep the
parsing of pin configuration subnodes consistent with other Qualcomm
schemas (children named with '-state' suffix, their children with
'-pins').

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20221019001351.1630089-5-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>