iommu/mediatek: Allow IOMMU_DOMAIN_UNMANAGED for PCIe VFIO

Allow the type IOMMU_DOMAIN_UNMANAGED since vfio_iommu_type1.c always call
iommu_domain_alloc. The PCIe EP works ok when going through vfio.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20220503071427.2285-20-yong.wu@mediatek.com


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