Add generated_pkt_steering_fail and handled_pkt_steering_fail to devlink
heatlth reporter.
generated_pkt_steering_fail indicates the number of packets dropped due to
illegal steering operation within the vport steering domain.
handled_pkt_steering_fail indicates the number of packets dropped due to
illegal steering operation, originated by the vport.
Also, update devlink reporter functionality documentation with the newly
exposed counters.