This patch supports the query of the link flow control parameter on a port. The command format is as follows: show port <port_id> flow_ctrl Signed-off-by: Huisong Li <lihuisong@huawei.com> Signed-off-by: Min Hu (Connor) <humin29@huawei.com> Acked-by: Xiaoyun Li <xiaoyun.li@intel.com> Acked-by: Kevin Traynor <ktraynor@redhat.com>