spi: dt-bindings: mtk-snfi: Add read latch latency property

Add mediatek,rx-latch-latency-ns property which adjust data read
latch latency in the unit of nanoseconds.

Signed-off-by: Xiangsheng Hou <xiangsheng.hou@mediatek.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230201020921.26712-6-xiangsheng.hou@mediatek.com


Signed-off-by: Mark Brown <broonie@kernel.org>