media: mediatek: vcodec: add h264 decoder driver for mt8186

Add h264 decode driver to support mt8186. For the architecture
is single core, need to add new interface to decode.

Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>