Switch hacking.checks from neutron to neutron_lib

Per armax recommendation in https://review.openstack.org/#/c/374425/,
moving away from the neutron hacking checks, using neutron_lib hacking
checks instead.

We need to bypass N530 (direct neutron imports not allowed) for the
forseeable future.

Change-Id: I05804844445575a55ab33273b88fd3a5ff9df179
Closes-Bug: #1626298

networking_powervm/hacking/checks.py

@@ -14,7 +14,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from neutron.hacking import checks
+from neutron_lib.hacking import checks
 
 
 def no_log_warn(logical_line):

tox.ini

@@ -65,7 +65,8 @@ whitelist_externals = bash
 [flake8]
 # H405 multi line docstring summary not separated with an empty line
 # TODO(marun) H404 multi line docstring should start with a summary
-ignore = H404,H405
+# N530 direct neutron imports not allowed
+ignore = H404,H405,N530
 show-source = true
 builtins = _
 exclude = .venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,build,tools,.ropeproject,rally-scenarios