utils/conv_gen.py: explicitly import reduce()

This change finally makes the script able to be executed
in Python 3 environment. Due to new Python 3 restrictions,
the reduce() should be imported explicitly.

Change-Id: Icbc81c29f1a226aeed2c1245a5d60809fe124005

utils/conv_gen.py

@@ -24,6 +24,7 @@ mod_license = """
 """
 
 import sys, os, math
+from functools import reduce
 
 class ConvolutionalCode(object):