fix and simplify hardware model detection

update_checker.py

@@ -10,12 +10,11 @@ import requests
 MAC_URL = 'http://macvendors.co/api/%s'
 
 def getHardwareModelFromEntry(d):
+    try: 
+        hardware_model = d["nodeinfo"]["hardware"]["model"]
+    except KeyError:
         hardware_model = "UNKNOWN"
-    if d != None:
-        if "nodeinfo" in d:
-            if "hardware" in d:
-                if "model" in d["hardware"]:
-                    hardware_model = d["hardware"]["model"]
+
     return hardware_model
 
 def ipv62mac(ipv6):