scsi: qla2xxx: Send Notify ACK after N2N PLOGI

qlt_handle_login schedules session for deletion even if a login is in
progress. That causes login bouncing, i.e. a few logins are made before it
settles down.

Complete the first login by sending Notify Acknowledge IOCB via
qlt_plogi_ack_unref if the session is pending login completion.

Fixes: 9cd883f ("scsi: qla2xxx: Fix session cleanup for N2N")
Cc: Krishna Kant <krishna.kant@purestorage.com>
Cc: Alexei Potashnik <alexei@purestorage.com>
Link: https://lore.kernel.org/r/20191125165702.1013-11-r.bolshakov@yadro.com
Acked-by: Quinn Tran <qutran@marvell.com>
Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_target.c

@@ -4803,6 +4803,7 @@ static int qlt_handle_login(struct scsi_qla_host *vha,
 
 	switch (sess->disc_state) {
 	case DSC_DELETED:
+	case DSC_LOGIN_PEND:
 		qlt_plogi_ack_unref(vha, pla);
 		break;