ARM: dts: rockchip: Add 3V3_SYS regulator for edgeble-neu2

Edgeble Neu2 IO board has 3V3_SYS regulator to power Audio, RS485,
and 4G Module.

Add regulator for it.

Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Link: https://lore.kernel.org/r/20230731103518.2906147-13-jagan@edgeble.ai


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