dt-bindings: pinctrl: qcom: Add bindings for MDM9607

Document the newly added MDM9607 pinctrl driver.

Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210624191743.617073-1-konrad.dybcio@somainline.org


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