vfio: convert to 128 bit arithmetic calculations when adding mem regions

vfio_listener_region_add for a iommu mr results in
an overflow assert since iommu memory region is initialized
with UINT64_MAX. Convert calculations to 128 bit arithmetic
for iommu memory regions and let int128_get64 assert for non iommu
regions if there's an overflow.

Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bandan Das <bsd@redhat.com>
[missed (end - 1) on 2nd trace call, move llsize closer to use]
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
