With the IOMMU ops now looking much the same shape as iommu_dma_ops,
switch them out in favour of the iommu-dma library, currently enhanced
with temporary workarounds that allow it to also sit underneath the
arch-specific API. With that in place, we can now start converting the
remaining IOMMU drivers and consumers to work with IOMMU API default
domains instead.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>