arm64: dts: rockchip: Add Nanopi NEO4 initial support

FriendlyElec NanoPi NEO4 is known to be a revision 4 based
NanoPi4 series of boards.

Most of know peripherals are shared between Nanopi M4 vs NEO4, except
- 1GB DDR3
- USB Host ports
- Missing DSI port
- USB 2.0 Host with USB2PHY0 (no USB2PH1)

Add support for it, by reusing existing rk3399-nanopi4.dtsi

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Akash Gajjar <akash@openedev.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>