RDMA/hns: Use GFP_ATOMIC in hns_roce_v2_modify_qp

The the below commit, hns_roce_v2_modify_qp is called inside spinlock
while using GFP_KERNEL. Change it to GFP_ATOMIC.

Fixes: 0425e3e6 ("RDMA/hns: Support flush cqe for hip08 in kernel space")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>