media: mtk-mdp: Use correct aliases name

aliases property name must include only lowercase and '-'. Fix in dts
and driver.

Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>