arm64: dts: rockchip: Add DT node for ADC support in RK3588

Add DT node for ADC support in RK3588.

Signed-off-by: Shreeya Patel <shreeya.patel@collabora.com>
Link: https://lore.kernel.org/r/20230603185340.13838-8-shreeya.patel@collabora.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>