arm64: dts: allwinner: h6: Add HDMI pipeline

This commit adds all entries needed for HDMI to function properly.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
[added DE3 bus]
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>