dt-bindings: media: mediatek: mdp3: merge the indentical RDMA under display

dt-bindings: media: mediatek: mdp3: merge the indentical RDMA under display

To simplify maintenance and avoid branches, the identical component
should be merged and placed in the path belonging to the MDP
(from display/* to media/*).

In addition, currently only MDP utilizes RDMA through CMDQ, and the
necessary properties for "mediatek,gce-events", and "mboxes" have been
set up for this purpose.
Within DISP, it directly receives component interrupt signals.

Signed-off-by: Moudy Ho <moudy.ho@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>