drm/mediatek: mtk_hdmi: Convert to module_platform_driver macro

drm/mediatek: mtk_hdmi: Convert to module_platform_driver macro

Now that all of the mtk_hdmi subdrivers are a platform driver on
their own it is possible to remove the custom init/exit functions
in this driver and just use the module_platform_driver() macro.

While at it, also compress struct of_device_id entries and remove
stray commas in mtk_hdmi_driver assignments.

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20250415104321.51149-7-angelogioacchino.delregno@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>