media: mediatek: vcodec: disable vp8 4K capability

For vp8 not support 4K, need to disable it.

Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>