RDMA/hns: Bugfix for data type of dip_idx

RDMA/hns: Bugfix for data type of dip_idx

dip_idx is associated with qp_num whose data type is u32. However, dip_idx
is incorrectly defined as u8 data in the hns_roce_dip struct, which leads
to data truncation during value assignment.

Fixes: f91696f2f053 ("RDMA/hns: Support congestion control type selection according to the FW")
Link: https://lore.kernel.org/r/1629884592-23424-2-git-send-email-liangwenpeng@huawei.com
Signed-off-by: Junxian Huang <huangjunxian4@hisilicon.com>
Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>