dt-bindings: pinctrl: qcom: Add sm8250 lpass lpi pinctrl bindings

Add device tree binding Documentation details for Qualcomm SM8250
LPASS(Low Power Audio Sub System) LPI(Low Power Island) pinctrl driver.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20201202163443.26499-2-srinivas.kandagatla@linaro.org


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