media: dt-bindings: mediatek: vcodec: Add the platform compatible to schema

There are venc node warnings when running dtbs_check, the clock-names
was unexpected, missing properties '#address-cells' and '#size-cells'.
Add the corresponding platform compatible to schema.

Signed-off-by: Irui Wang <irui.wang@mediatek.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>