iommu/io-pgtable-arm: Use address conversion consistently

iommu/io-pgtable-arm: Use address conversion consistently

Use consistent address conversions in the driver:
- virt_to_phys(): For all virtual to physical address conversion,
  convert __pa users as we don’t need to rely on it type casting.
- phys_to_virt(): For all physical to virtual address conversion,
  similarly, convert __va users.

That changes nothing at all. However, it will be useful when
compiling this file for the KVM hypervisor as it can cleanly
replace virt_to_phys/phys_to_virt

Signed-off-by: Mostafa Saleh <smostafa@google.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>