Align scp and vpu firmware interface, remove the depedency for
'struct mtk_vcodec_dev' and 'struct mtk_vcodec_ctx'. It will be
much easier to separate video encoder and decoder.
Signed-off-by: Yunfei Dong <yunfei.dong@xxxxxxxxxxxx>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>