RDMA/hns: Fix unnecessary err return when using invalid congest control algorithm

RDMA/hns: Fix unnecessary err return when using invalid congest control algorithm

[ Upstream commit efb9cbf66440482ceaa90493d648226ab7ec2ebf ]

Add a default congest control algorithm so that driver won't return
an error when the configured algorithm is invalid.

Fixes: f91696f2f053 ("RDMA/hns: Support congestion control type selection according to the FW")
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Link: https://lore.kernel.org/r/20231028093242.670325-1-huangjunxian6@hisilicon.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>