soc: mediatek: mtk-mmsys: Split out MT8173 mmsys DDP routing table

MT2701, MT2712 and MT8173 were relying on a "default" DDP I/O routing
table, describing all of the possible connections between display block
components: while this is definitely working it's suboptimal for the
actual routing description, as we may be enabling outputs and inputs
that are not needed, possibly impacting on actual DDP performance other
than slightly prolonging boot times by having to parse a table that is
bigger than needed.

Seen that all of the other supported SoCs have got their own table and
seen that a comment in mtk-mmsys.h explicitly mentions that the wanted
way is to have one table per SoC, create a new routing table that is
specifically tailored to MT8173 and, while at it, remove mentions to
said SoC from the comment in mtk-mmsys.h.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230309102618.114157-2-angelogioacchino.delregno@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>