media: mediatek: vcodec: remove the dependency of vcodec debug log

'mtk_vcodec_debug' and 'mtk_vcodec_err' depends on 'mtk_vcodec_ctx'
to get the index of each instance. Define two different macro
mtk_vdec_debug and mtk_venc_debug for decoder and encoder, and re-write
macro mtk_vcodec_debug as the common interface which is called
by mtk_vdec_debug and mtk_venc_debug. The vcodec debug log can be
separeated by encoder and decoder.

Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>