RDMA/umem: Fix truncation for block sizes >= 4G

RDMA/umem: Fix truncation for block sizes >= 4G

When the iommu is used the linearization of the mapping can give a single
block that is very large split across multiple SG entries.

When __rdma_block_iter_next() reassembles the split SG entries it is
overflowing the 32 bit stack values and computed the wrong DMA addresses
for blocks after the truncation.

Use the right types to hold DMA addresses.

Link: https://patch.msgid.link/r/1-v1-88303e9e509f+f7-ib_umem_types_jgg@nvidia.com
Cc: stable@vger.kernel.org
Fixes: a808273a495c ("RDMA/verbs: Add a DMA iterator to return aligned contiguous memory blocks")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>