iommu_pt: Fix pgsize_bitmap calculation in get_info for smaller vasz's

iommu_pt: Fix pgsize_bitmap calculation in get_info for smaller vasz's

To properly enforce the domain VA limit, clamp pgsize_bitmap using the
requested max_vasz_lg2 in get_info().
Apply the same VA limit as get_info() in the kunit possible_sizes test so
assertions stay consistent with the domain bitmap.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Ankit Soni <Ankit.Soni@amd.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>