drm/mediatek: mtk_hdmi: Fix probe device leaks

drm/mediatek: mtk_hdmi: Fix probe device leaks

Make sure to drop the references to the DDC adapter and CEC device
taken during probe on probe failure (e.g. probe deferral) and on driver
unbind.

Fixes: 8f83f26891e1 ("drm/mediatek: Add HDMI support")
Cc: stable@vger.kernel.org	# 4.8
Cc: Jie Qiu <jie.qiu@mediatek.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20250923152340.18234-5-johan@kernel.org/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>