media: dt-bindings: media: mediatek: vcodec: Change the max reg value to 2

Need to add racing control register base in device node for mt8195 support
inner racing mode. Changing the max reg value from 1 to 2.

Adding the description for VDEC_SYS and VDEC_MISC.

Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>