iommufd: Rename uptr in iopt_alloc_iova()

iommufd: Rename uptr in iopt_alloc_iova()

iopt_alloc_iova() takes a uptr argument but only checks for its alignment.
Generalize this to an unsigned address, which can be the offset from the
start of a file in a subsequent patch.  No functional change.

Link: https://patch.msgid.link/r/1729861919-234514-3-git-send-email-steven.sistare@oracle.com
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>