iommupt: Fix the end_index calculation in __map_range_leaf()

iommupt: Fix the end_index calculation in __map_range_leaf()

Sashiko noticed a mismatch of units in this math: num_leaves is
actually the number of leaf *entries* (so a 16-item contiguous leaf
is one num_leaves), while index is in items. The mismatch in maths
causes __map_range_leaf() to exit early instead of efficiently
filling a larger range of contiguous PTEs.

The early exit is caught by the functions above and then
__map_range_leaf() is re-invoked, so there is no functional issue.

Correct the misuse of units by adjusting num_leaves with the leaf
size and avoid the performance cost of looping externally.

There are also some mismatched types for num_leaves; simplify
things to remove the duplicated calculations.

Fixes: d6c65b0fd621 ("iommupt: Avoid rewalking during map")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewd-by: Pranjal Shrivastava <praan@google.com>
Tested-by: Josua Mayer <josua@solid-run.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>