dt-bindings: rtc: Convert rtc-fsl-ftm-alarm.txt to yaml format

Convert dt-binding doc "rtc-fsl-ftm-alarm.txt" to yaml format.

Change example's reg to 32bit address and length.
Remove unrelated rcpm@1e34040 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/20240528184359.2685109-1-Frank.Li@nxp.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>