iommu: push use of type-safe DFN and MFN into iommu_ops

iommu: push use of type-safe DFN and MFN into iommu_ops

This patch modifies the methods in struct iommu_ops to use type-safe DFN
and MFN. This follows on from the prior patch that modified the functions
exported in xen/iommu.h.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Acked-by: Julien Grall <julien.grall@arm.com>