pyloxi: move pack_list to generic_util

For consistency with unpack_list.
diff --git a/py_gen/oftype.py b/py_gen/oftype.py
index 9718a9f..40bcb40 100644
--- a/py_gen/oftype.py
+++ b/py_gen/oftype.py
@@ -148,7 +148,7 @@
 # Special case for lists of hello_elem, which must ignore unknown types
 type_data_map['list(of_hello_elem_t)'] = OFTypeData(
     init='[]',
-    pack='util.pack_list(%s)',
+    pack='loxi.generic_util.pack_list(%s)',
     unpack='util.unpack_list_hello_elem(%s)')
 
 ## Public interface
@@ -175,7 +175,7 @@
     if type_data and type_data.pack:
         return type_data.pack % value_expr
     elif oftype_is_list(oftype):
-        return "util.pack_list(%s)" % value_expr
+        return "loxi.generic_util.pack_list(%s)" % value_expr
     else:
         return "loxi.unimplemented('pack %s')" % oftype
 
diff --git a/py_gen/templates/generic_util.py b/py_gen/templates/generic_util.py
index 99840ec..039d82a 100644
--- a/py_gen/templates/generic_util.py
+++ b/py_gen/templates/generic_util.py
@@ -35,6 +35,9 @@
 import loxi
 import struct
 
+def pack_list(values):
+    return "".join([x.pack() for x in values])
+
 def unpack_list(reader, deserializer):
     """
     The deserializer function should take an OFReader and return the new object.
diff --git a/py_gen/templates/util.py b/py_gen/templates/util.py
index 9c9ccc1..8ad246a 100644
--- a/py_gen/templates/util.py
+++ b/py_gen/templates/util.py
@@ -151,9 +151,6 @@
     return reader.read("!Q")[0]
 :: #endif
 
-def pack_list(values):
-    return "".join([x.pack() for x in values])
-
 MASK64 = (1 << 64) - 1
 
 def pack_bitmap_128(value):