dt-bindings: pinctrl: qcom: Add SDM660 LPI pinctrl

Add bindings for pin controller in SDM660 Low Power Audio SubSystem
(LPASS).

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Co-developed-by: Richard Acayan <mailingradian@gmail.com>
Signed-off-by: Richard Acayan <mailingradian@gmail.com>
Signed-off-by: Nickolay Goppen <setotau@mainlining.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>