dt-bindings: display: mediatek,dp: Allow DisplayPort AUX bus

Like others, the MediaTek DisplayPort controller provides an
auxiliary bus: import the common dp-aux-bus.yaml in this binding
to allow specifying an aux-bus subnode.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20250724083914.61351-3-angelogioacchino.delregno@collabora.com


Signed-off-by: Rob Herring (Arm) <robh@kernel.org>