RDMA/hns: Support DSCP

Add support for DSCP configuration. For DSCP, get dscp-prio mapping
via hns3 nic driver api .get_dscp_prio() and fill the SL (in WQE for
UD or in QPC for RC) with the priority value. The prio-tc mapping is
configured to HW by hns3 nic driver. HW will select a corresponding
TC according to SL and the prio-tc mapping.

Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Link: https://lore.kernel.org/r/20240315093551.1650088-1-huangjunxian6@hisilicon.com


Signed-off-by: Leon Romanovsky <leon@kernel.org>