Use unittest.mock instead of third party mock

Now that we no longer support py27, we can use the standard library
unittest.mock module instead of the third party mock lib.

Change-Id: Ibe31e2d17b8baf88c40e00e3beaa019b13594c7c
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

kuryr/tests/unit/binding/drivers/test_hw_veb.py

@@ -11,7 +11,8 @@
 # under the License.
 
 
-import mock
+from unittest import mock
+
 from oslo_utils import uuidutils
 
 from kuryr.lib.binding.drivers import hw_veb

kuryr/tests/unit/binding/drivers/test_ipvlan.py

@@ -11,7 +11,8 @@
 # under the License.
 
 
-import mock
+from unittest import mock
+
 from oslo_utils import uuidutils
 
 from kuryr.lib.binding.drivers import ipvlan

kuryr/tests/unit/binding/drivers/test_macvlan.py

@@ -11,7 +11,8 @@
 # under the License.
 
 
-import mock
+from unittest import mock
+
 from oslo_utils import uuidutils
 
 from kuryr.lib.binding.drivers import macvlan

kuryr/tests/unit/binding/drivers/test_nested.py

@@ -11,7 +11,8 @@
 # under the License.
 
 
-import mock
+from unittest import mock
+
 from oslo_utils import uuidutils
 
 from kuryr.lib.binding.drivers import nested

kuryr/tests/unit/binding/drivers/test_utils.py

@@ -9,8 +9,9 @@
 #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #    License for the specific language governing permissions and limitations
 #    under the License.
+from unittest import mock
+
 import ddt
-import mock
 from oslo_utils import uuidutils
 
 import pyroute2.ipdb.interfaces

kuryr/tests/unit/binding/drivers/test_veth.py

@@ -11,7 +11,8 @@
 # under the License.
 
 
-import mock
+from unittest import mock
+
 from oslo_utils import uuidutils
 
 from kuryr.lib.binding.drivers import veth

kuryr/tests/unit/binding/drivers/test_vlan.py

@@ -11,7 +11,8 @@
 # under the License.
 
 
-import mock
+from unittest import mock
+
 from oslo_utils import uuidutils
 
 from kuryr.lib.binding.drivers import vlan

kuryr/tests/unit/segmentation_type_drivers/test_vlan.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import mock
+from unittest import mock
 
 from oslo_config import cfg
 from six import moves

kuryr/tests/unit/test_opts.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from kuryr.lib import opts as kuryr_opts
 from kuryr.tests.unit import base

kuryr/tests/unit/test_utils.py

@@ -10,8 +10,9 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from unittest import mock
+
 import ddt
-import mock
 import socket
 
 from oslo_config import cfg