Skip VIF tests for standalone ironic

Consider standalone Ironic environment as Neutron-less.
Skip VIF tests because they fail in standalone Ironic.

Change-Id: I55e78712b74ca074e5ff18a885a3057b1072fed0
diff --git a/ironic_tempest_plugin/tests/api/admin/test_nodes.py b/ironic_tempest_plugin/tests/api/admin/test_nodes.py
index 2efa66e..dd7bf91 100644
--- a/ironic_tempest_plugin/tests/api/admin/test_nodes.py
+++ b/ironic_tempest_plugin/tests/api/admin/test_nodes.py
@@ -11,6 +11,8 @@
 #    under the License.
 
 import six
+
+from tempest import config
 from tempest.lib.common.utils import data_utils
 from tempest.lib import decorators
 from tempest.lib import exceptions as lib_exc
@@ -19,6 +21,8 @@
 from ironic_tempest_plugin.tests.api.admin import api_microversion_fixture
 from ironic_tempest_plugin.tests.api.admin import base
 
+CONF = config.CONF
+
 
 class TestNodes(base.BaseBaremetalTest):
     """Tests for baremetal nodes."""
@@ -166,6 +170,12 @@
 
     min_microversion = '1.28'
 
+    @classmethod
+    def skip_checks(cls):
+        super(TestNodesVif, cls).skip_checks()
+        if not CONF.service_available.neutron:
+            raise cls.skipException('Neutron is not enabled.')
+
     def setUp(self):
         super(TestNodesVif, self).setUp()