Using real serial_number when looking up OLT

Change-Id: Ie51676c56df08e98a3cf338b9a57c061b36900ff
diff --git a/sadisTypes.go b/sadisTypes.go
index 96ac92c..b28c1f7 100644
--- a/sadisTypes.go
+++ b/sadisTypes.go
@@ -73,10 +73,11 @@
   XOS vOLT device format
 */
 type oltDevice struct {
-	Uplink string `json:"uplink"`
-	Host   string `json:"host"`
-	Port   int    `json:"port"`
-	NasID  string `json:"nas_id"`
+	Uplink       string `json:"uplink"`
+	Host         string `json:"host"`
+	Port         int    `json:"port"`
+	NasID        string `json:"nas_id"`
+	SerialNumber string `json:"serial_number"`
 }
 
 type oltDevices struct {