dt-bindings: pwm: fsl-ftm: Convert to yaml format

Convert dt-bindings pwm-fsl-ftm.txt to yaml format.

Additional change during convert:
- "big-endian" is not required property.
- Add "sleep" to pinctrl-names.
- Change pinctrl-NNN to pinctrl-0 and pinctrl-1.
- Remove label "pwm0" in example.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240528202025.2919358-1-Frank.Li@nxp.com


Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>