RDMA/hns: Init the variable at the suitable place

Assigning a value to ret in the init statement of a for-loop makes the
code less readable.

Link: https://lore.kernel.org/r/20220409083254.9696-6-liangwenpeng@huawei.com
Signed-off-by: Haoyue Xu <xuhaoyue1@hisilicon.com>
Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>