With the VIOT support in place, x86 platforms can now use the
virtio-iommu.
Because the other x86 IOMMU drivers aren't yet ready to use the
acpi_dma_setup() path, x86 doesn't implement arch_setup_dma_ops() at the
moment. Similarly to Vt-d and AMD IOMMU, call iommu_setup_dma_ops() from
probe_finali
With the built-in topology description in place, x86 platforms can now
use the virtio-iommu.
Architectures that use the generic iommu_dma_ops should normally select
CONFIG_IOMMU_DMA themselves (from arch/*/Kconfig). Since not all x86
drivers have been converted yet, it's currently up to the IOMMU
