media: dt-bindings: media: document mediatek,mt8183-vcodec-enc

MT8183's encoder is similar to MT8173's.

Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>