dt-bindings: iommu: mediatek: Convert IOMMU to DT schema

Convert MediaTek IOMMU to DT schema.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-2-yong.wu@mediatek.com


Signed-off-by: Will Deacon <will@kernel.org>