arm64: dts: rockchip: define iodomains for rk3368-lion

This is not strictly needed, as 3.3V is the default,
but good to have for descriptive purposes nevertheless.

Signed-off-by: Jakob Unterwurzacher <jakob.unterwurzacher@theobroma-systems.com>
[fixed ordering]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20210922230429.2162535-2-heiko@sntech.de