arm64: dts: mediatek: cherry: Add edptx and dptx support

arm64: dts: mediatek: cherry: Add edptx and dptx support

In cherry projects, we use edptx as the internal display interface
and use dptx as the external display interface. To support this, we
need to add more properties.

- Add pinctrls for edptx and dptx.
- Add ports for edptx and dptx.

The port connections for the internal and external display:
dp-intf0 -> edptx -> panel
dp-intf1 -> dptx

The edptx endpoint is kept empty for now, as the panel addition will
come in a later commit.

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20221110063716.25677-5-rex-bc.chen@mediatek.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>