RDMA/hns: Remove unnecessary check for the sgid_attr when modifying QP

The sgid_attr cannot be null in this scenario. This judgment is redundant.

Fixes: 606bf89e ("RDMA/hns: Refactor for hns_roce_v2_modify_qp function")
Link: https://lore.kernel.org/r/20220409083254.9696-2-liangwenpeng@huawei.com


Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>