RDMA/hns: Reduce PFC frames in congestion scenarios

The original value means sending 16 packets at a time, and it should be
configured to 0 which means sending 1 packet instead. It is modified to
reduce the number of PFC frames to make sure the performance meets
expectations when flow control is enabled on hip08.

Link: https://lore.kernel.org/r/1585194018-4381-2-git-send-email-liweihang@huawei.com
Signed-off-by: Jihua Tao <taojihua4@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -3928,7 +3928,7 @@ static int modify_qp_init_to_rtr(struct ib_qp *ibqp,
 
 	/* mtu*(2^LP_PKTN_INI) should not bigger than 1 message length 64kb */
 	roce_set_field(context->byte_56_dqpn_err, V2_QPC_BYTE_56_LP_PKTN_INI_M,
-		       V2_QPC_BYTE_56_LP_PKTN_INI_S, 4);
+		       V2_QPC_BYTE_56_LP_PKTN_INI_S, 0);
 	roce_set_field(qpc_mask->byte_56_dqpn_err, V2_QPC_BYTE_56_LP_PKTN_INI_M,
 		       V2_QPC_BYTE_56_LP_PKTN_INI_S, 0);