nvmet-tcp: fix unhandled tcp states in nvmet_tcp_state_change()
TCP_FIN_WAIT2 and TCP_LAST_ACK were not handled, the connection is closing
so we can ignore them and avoid printing the "unhandled state"
warning message.
[ 1298.852386] nvmet_tcp: queue 2 unhandled state 5
[ 1298.879112] nvmet_tcp: queue 7 unhandled state 5
[ 1298.884253] nvmet_tcp: queue 8 unhandled state 5
[ 1298.889475] nvmet_tcp: queue 9 unhandled state 5
v2: Do not call nvmet_tcp_schedule_release_queue(), just ignore
the fin_wait2 and last_ack states.