iommu/mediatek: Introduce new flag TF_PORT_TO_ADDR_MT8173

In preparation for adding support for MT6795, add a new flag named
TF_PORT_TO_ADDR_MT8173 and use that instead of checking for m4u_plat
type in mtk_iommu_hw_init() to avoid seeing a long list of m4u_plat
checks there in the future.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20220913151148.412312-3-angelogioacchino.delregno@collabora.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>