media: dt-bindings: media: mediatek: vcodec: Adds decoder dt-bindings for mt8186

Adds decoder dt-bindings for mt8186.

Signed-off-by: Yunfei Dong <yunfei.dong@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@kernel.org>