Fixes brick Nova pep8 violation for lvm.py

Running pep8 tests in Nova gives a violation
in lvm.py for not importing a module.  This
is a simple fix to import the module itself
instead of only importing a function in the
module.

Fixes bug #1220849

Change-Id: Idc603dcfab18601dd4246c623d34be5933434f84

cinder/brick/local_dev/lvm.py

@@ -22,7 +22,7 @@
 import math
 import re
 
-from itertools import izip
+import itertools
 
 from cinder.brick import exception
 from cinder.brick import executor
@@ -169,7 +169,7 @@ def get_all_volumes(root_helper, vg_name=None, no_suffix=True):
         lv_list = []
         if out is not None:
             volumes = out.split()
-            for vg, name, size in izip(*[iter(volumes)] * 3):
+            for vg, name, size in itertools.izip(*[iter(volumes)] * 3):
                 lv_list.append({"vg": vg, "name": name, "size": size})
 
         return lv_list