dt-bindings: firmware: Support SCMI pinctrl protocol

Add SCMI v3.2 pinctrl protocol bindings with an example.

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20240418-pinctrl-scmi-v11-2-499dca9864a7@nxp.com


Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>