fix wrong key name in test code
fix wrong key name in test code

test_default_root_device_name() in
nova/tests/unit/virt/libvirt/test_driver.py,
'detination_type' should be 'destination_type'.

Change-Id: Iba73e582d36fa16f563a8e806073a06f857e1078
Closes-Bug: #1577758

mahak/nova,rajalokan/nova,vmturbo/nova,rajalokan/nova,gooddata/openstack-nova,klmitch/nova,rahulunair/nova,gooddata/openstack-nova,mahak/nova,openstack/nova,rajalokan/nova,mikalstill/nova,Juniper/nova,openstack/nova,gooddata/openstack-nova,openstack/nova,Juniper/nova,sebrandon1/nova,alaski/nova,vmturbo/nova,mahak/nova,sebrandon1/nova,bigswitch/nova,Juniper/nova,bigswitch/nova,jianghuaw/nova,rahulunair/nova,sebrandon1/nova,hanlind/nova,klmitch/nova,mikalstill/nova,rajalokan/nova,hanlind/nova,klmitch/nova,alaski/nova,mikalstill/nova,klmitch/nova,hanlind/nova,jianghuaw/nova,rahulunair/nova,vmturbo/nova,phenoxim/nova,cloudbase/nova,jianghuaw/nova,cloudbase/nova,vmturbo/nova,Juniper/nova,cloudbase/nova,jianghuaw/nova,phenoxim/nova,gooddata/openstack-nova