dt-bindings: pinctrl: qcom,mdm9607: drop ref to pinctrl.yaml

The binding references common Qualcomm TLMM pin controller schema, which
references pinctrl.yaml.

Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20221017230012.47878-2-krzysztof.kozlowski@linaro.org


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