RDMA/hns: Remove redundant variable "ret"

It is completely redundant for this function to use "ret" to store the
return value of the subfunction.

Link: https://lore.kernel.org/r/20220409083254.9696-4-liangwenpeng@huawei.com
Signed-off-by: Guofeng Yue <yueguofeng@hisilicon.com>
Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>