media: dt-bindings: media: add 'assigned-clocks' to vcodec examples

Fix MTK binding document for MT8173 dtsi changed in order
to use standard CCF interface.
MT8173 SoC from Mediatek.

Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Signed-off-by: Qianqian Yan <qianqian.yan@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>