iommu/virtio: Pass end address to viommu_add_mapping()

iommu/virtio: Pass end address to viommu_add_mapping()

To support identity mappings, the virtio-iommu driver must be able to
represent full 64-bit ranges internally. Pass (start, end) instead of
(start, size) to viommu_add/del_mapping().

Clean comments. The one about the returned size was never true: when
sweeping the whole address space the returned size will most certainly
be smaller than 2^64.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20211201173323.1045819-5-jean-philippe@linaro.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>