drm/mediatek: Fix aal size config

[ Upstream commit 71dcadba ]

The orginal setting is not correct, fix it to follow hardware data sheet.
If keep this error setting, mt8173/mt8183 display ok
but mt8192 display abnormal.

Fixes: 0664d139

 ("drm/mediatek: Add AAL engine basic function")

Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>