dt-bindings: interrupt-controller: Convert Synquacer EXIU to DT schema

Convert the Socionext Synquacer EXIU interrupt controller to DT schema
format.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221209171636.3351602-1-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>