fru_gen: fixes for python3

The iter{keys,items} functions have become just 'keys' and 'items'
in python3.  Python2 also has keys and items, which is slightly
less efficient for iteration but none of these maps are large enough
to be of concern.

Change-Id: If6e8f36ad39074e0a6c022fb09e3a43b0928af19
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/scripts/writefru.mako.cpp b/scripts/writefru.mako.cpp
index 7573862..6180e13 100644
--- a/scripts/writefru.mako.cpp
+++ b/scripts/writefru.mako.cpp
@@ -3,18 +3,18 @@
 #include "frup.hpp"
 
 extern const FruMap frus = {
-% for key in fruDict.iterkeys():
+% for key in fruDict.keys():
    {${key},{
 <%
     fru = fruDict[key]
 %>
-    % for object,interfaces in fru.iteritems():
+    % for object,interfaces in fru.items():
          {"${object}",{
-         % for interface,properties in interfaces.iteritems():
+         % for interface,properties in interfaces.items():
              {"${interface}",{
-            % for dbus_property,property_value in properties.iteritems():
+            % for dbus_property,property_value in properties.items():
                  {"${dbus_property}",{
-                % for name,value in property_value.iteritems():
+                % for name,value in property_value.items():
                      {"${name}","${value}"},
                 % endfor
                  }},