Use other item instead of security_group in network-quotas test

In network/admin/test_quotas, it uses {'security_group': 0} for
new quotas, but if neutron's security_group extension is not
enabled, the testcase will fail unexpectedly.

As we are just testing neutron's quotas, we can choose quota items
that are common to all environments such as 'network' and 'port',
thus the testcase will work happily even if neutron's security-group
extension is not enabled.

Change-Id: I9147ea1c151672b25a25ceee6a541ddf7f04a8cd
diff --git a/tempest/api/network/admin/test_quotas.py b/tempest/api/network/admin/test_quotas.py
index 2ff31e0..3a264ff 100644
--- a/tempest/api/network/admin/test_quotas.py
+++ b/tempest/api/network/admin/test_quotas.py
@@ -87,5 +87,5 @@
 
     @test.idempotent_id('2390f766-836d-40ef-9aeb-e810d78207fb')
     def test_quotas(self):
-        new_quotas = {'network': 0, 'security_group': 0}
+        new_quotas = {'network': 0, 'port': 0}
         self._check_quotas(new_quotas)