dt-bindings: i3c: add header for generic I3C flags

Add header file for generic I3C flags to avoid hard code in dts file.

Signed-off-by: Carlos Song <carlos.song@nxp.com>
Reviewed-by: Frank Li <frank.li@nxp.com>
Acked-by: Jason Liu <jason.hui.liu@nxp.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240715225351.3237284-1-Frank.Li@nxp.com


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