media: mtk-jpegdec: refactor jpegdec func interface

refactor the func interface of mtk_jpeg_dec_set_config
for decode

Signed-off-by: kyrie wu <kyrie.wu@mediatek.com>
Signed-off-by: irui wang <irui.wang@mediatek.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>