dt-bindings: mediatek: add compatible for mt8183 pwrap

This adds dt-binding documentation of pwrap for Mediatek MT8183 SoC
Platform.

Signed-off-by: Hsin-Hsiung Wang <hsin-hsiung.wang@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>