rdma: Add "stat qp show" support

rdma: Add "stat qp show" support

This patch presents link, id, task name, lqpn, as well as all sub
counters of a QP counter.
A QP counter is a dynamically allocated statistic counter that is
bound with one or more QPs. It has several sub-counters, each is
used for a different purpose.

Examples:
$ rdma stat qp show
link mlx5_2/1 cntn 5 pid 31609 comm client.1 rx_write_requests 0
rx_read_requests 0 rx_atomic_requests 0 out_of_buffer 0 out_of_sequence 0
duplicate_request 0 rnr_nak_retry_err 0 packet_seq_err 0
implied_nak_seq_err 0 local_ack_timeout_err 0 resp_local_length_error 0
resp_cqe_error 0 req_cqe_error 0 req_remote_invalid_request 0
req_remote_access_errors 0 resp_remote_access_errors 0
resp_cqe_flush_error 0 req_cqe_flush_error 0
    LQPN: <178>
$ rdma stat show link rocep1s0f5/1
link rocep1s0f5/1 rx_write_requests 0 rx_read_requests 0 rx_atomic_requests 0 out_of_buffer 0 duplicate_request 0
rnr_nak_retry_err 0 packet_seq_err 0 implied_nak_seq_err 0 local_ack_timeout_err 0 resp_local_length_error 0 resp_cqe_error 0
req_cqe_error 0 req_remote_invalid_request 0 req_remote_access_errors 0 resp_remote_access_errors 0 resp_cqe_flush_error 0
req_cqe_flush_error 0 rp_cnp_ignored 0 rp_cnp_handled 0 np_ecn_marked_roce_packets 0 np_cnp_sent 0
$ rdma stat show link rocep1s0f5/1 -p
link rocep1s0f5/1
    rx_write_requests 0
    rx_read_requests 0
    rx_atomic_requests 0
    out_of_buffer 0
    duplicate_request 0
    rnr_nak_retry_err 0
    packet_seq_err 0
    implied_nak_seq_err 0
    local_ack_timeout_err 0
    resp_local_length_error 0
    resp_cqe_error 0
    req_cqe_error 0
    req_remote_invalid_request 0
    req_remote_access_errors 0
    resp_remote_access_errors 0
    resp_cqe_flush_error 0
    req_cqe_flush_error 0
    rp_cnp_ignored 0
    rp_cnp_handled 0
    np_ecn_marked_roce_packets 0
    np_cnp_sent 0

Signed-off-by: Mark Zhang <markz@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>