arm64: dts: allwinner: h6: orangepi: Enable HDMI

Both, OrangePi One Plus and OrangePi Lite 2 have HDMI output. Enable it
in common DTSI.

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>