RDMA/hns: Remove redundant 'attr_mask' in modify_qp_init_to_init()

The attr_mask variable is not used in the function,
so remove it.

Link: https://lore.kernel.org/r/20220922123315.3732205-5-xuhaoyue1@hisilicon.com


Signed-off-by: Yixing Liu <liuyixing1@huawei.com>
Signed-off-by: Haoyue Xu <xuhaoyue1@hisilicon.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>