dt-bindings: media: mediatek: mdp3: correct RDMA and WROT node with generic names

The DMA-related nodes RDMA/WROT in MDP3 should be changed to generic names.
In addition, fix improper space indent in example.

Fixes: 4ad7b396 ("media: dt-binding: mediatek: add bindings for MediaTek MDP3 components")
Signed-off-by: Moudy Ho <moudy.ho@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>