dt-bindings: arm: sunxi: add ICnova A20 ADB4006 binding

Document board compatible names for In-Circuit ICnova A20 ADB4006
development board.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Ludwig Kormann <ludwig.kormann@ict42.de>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20230510111528.2155582-2-ludwig.kormann@ict42.de


Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>