media: mediatek: vcodec: Get the chip name for each platform

Store the name of the chip in the context of the driver in order
to be able to choose the correct configuration values for the
different codecs.
Use a enum value instead of an integer to store a more descriptive name.

Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>