dt-bindings: arm: amlogic: add board AN400

Add the board AN400 tree bindings based Amloigc T7 SoC.

Signed-off-by: Xianwei Zhao <xianwei.zhao@amlogic.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230706091954.3301224-2-xianwei.zhao@amlogic.com


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>