Py3 replace dict.iteritems with six.iteritems
Py3 replace dict.iteritems with six.iteritems

All dict.iteritems in osc are replaced with six.iteritems
except this one.
So fix it to add py3 compatibility.

Change-Id: I1aa51399a36e650d262d839ce2b4ec04d3f91db2

dtroyer/python-openstackclient,openstack/python-openstackclient,redhat-openstack/python-openstackclient,openstack/python-openstackclient,redhat-openstack/python-openstackclient,dtroyer/python-openstackclient