dt-bindings: display: mediatek: dpi: Add DP_INTF compatible

DP_INTF is similar to DPI but does not have the exact same feature set
or register layouts.

DP_INTF is the sink of the display pipeline that is connected to the
DisplayPort controller and encoder unit. It takes the same clocks as
DPI.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20220701035845.16458-2-rex-bc.chen@mediatek.com/


Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>