dt-bindings: pinctrl: convert nxp,lpc1850-scu.txt to yaml format

Convert nxp,lpc1850-scu.txt to yaml format.

Additional changes:
- keep child name *_cfg to align legancy very old platform dts file.
- remove label in examples.
- just keep one examples.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/20250606160359.1356555-1-Frank.Li@nxp.com


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