arm64: dts: exynos: use 8-bit for SPI IR LED duty-cycle in TM2

The 'duty-cycle' of SPI IR LED property is u8:

  exynos/exynos5433-tm2e.dtb: irled@0: duty-cycle:0: [0, 0, 0, 60] is too long

Link: https://lore.kernel.org/r/20221204104242.117558-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>