[media] dt-bindings: mediatek: Add a binding for Mediatek JPEG Decoder

Add a DT binding documentation for Mediatek JPEG Decoder of
MT2701 SoC.

Signed-off-by: Rick Chang <rick.chang@mediatek.com>
Signed-off-by: Minghsiu Tsai <minghsiu.tsai@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>