RDMA/hns: Fix the issue of IOVA not page continuous in hip08

If the smmu is enabled, the length of sg obtained from
__iommu_map_sg_attrs is not 4kB. When the IOVA is set with the sg
dma address, the IOVA will not be page continuous. so, the current
code has MTPT configuration error that probably cause dma operation
failure. In order to fix this issue, the IOVA should be calculated
based on the sg length.

Fixes: 3958cc56("RDMA/hns: Configure the MTPT in hip08")
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Signed-off-by: Shaobo Xu <xushaobo2@huawei.com>
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Yixian Liu <liuyixian@huawei.com>
Signed-off-by: Xiping Zhang (Francis) <zhangxiping3@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>