ARM: dts: rockchip: fix rk3288 dp node

With the conversion of rockchip,analogix-dp.yaml a port@1 node
is required, so add a node with label edp_out.
Also restyle.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/0a423eb4-0ab6-7ecb-d450-d93639160dbc@gmail.com


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