arm64: dts: allwinner: h6: orangepi-one-plus: Enable ethernet

OrangePi One Plus has gigabit ethernet. Add nodes for it.

Signed-off-by: Marcus Cooper <codekipper@gmail.com>
[patch split and commit message]
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Christopher Obbard <chris@64studio.com>
Tested-by: Christopher Obbard <chris@64studio.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>