drm/mediatek: mtk_hdmi: Use devm managed version of drm_bridge_add

drm/mediatek: mtk_hdmi: Use devm managed version of drm_bridge_add

Simplify the probe/remove functions by using devm_drm_bridge_add()
as now there is no more need to manually remove the bridge.

Reviewed-by: CK Hu <ck.hu@mediatek.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20250217154836.108895-30-angelogioacchino.delregno@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>