drm/mediatek: mtk_hdmi: Fix inverted parameters in some regmap_update_bits calls

In mtk_hdmi driver, a recent change replaced custom register access
function calls by regmap ones, but two replacements by regmap_update_bits
were done incorrectly, because original offset and mask parameters were
inverted, so fix them.

Fixes: d6e25b35 ("drm/mediatek: hdmi: Use regmap instead of iomem for main registers")
Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20250818-mt8173-fix-hdmi-issue-v1-1-55aff9b0295d@collabora.com/


Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>