arm64: dts: mediatek: mt8183: Migrate to display controller OF graph

arm64: dts: mediatek: mt8183: Migrate to display controller OF graph

The display related IPs in MT8183 are flexible and support being
interconnected with different instances of DDP IPs forming a full
Display Data Path that ends with an actual display output, which
is board specific.

Add a common graph in the main mt8183.dtsi devicetree, which is
shared between all of the currently supported boards, and do it
such that only a very minimal amount of changes are needed to
each board - the only required change was done in mt8183-pumpkin,
using a phandle to assign the display to DPI0.

All boards featuring any display functionality will extend this
common graph to hook the display controller of the SoC to their
specific output port(s).

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20250724083914.61351-33-angelogioacchino.delregno@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>