media: mtk-vcodec: Use pure single core for MT8183

Separates different architecture for hardware: pure_sin_core
and lat_sin_core. MT8183 is pure single core. Uses .hw_arch to
distinguish.

Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>