Unskip test_update_port_with_second_ip()

test_update_port_with_second_ip() was skipped because of bug 1364166
which is now in a state which should allow us to unskip it.

Change-Id: I263bd4ef45ea02b18c6d00b6e27f0b12442be9ee
Related-Bug: #1364166
diff --git a/tempest/api/network/test_ports.py b/tempest/api/network/test_ports.py
index 26f6b8f..c6fe817 100644
--- a/tempest/api/network/test_ports.py
+++ b/tempest/api/network/test_ports.py
@@ -129,7 +129,6 @@
         for port in ports:
             self.assertEqual(sorted(fields), sorted(port.keys()))
 
-    @test.skip_because(bug="1364166")
     @test.attr(type='smoke')
     def test_update_port_with_second_ip(self):
         # Create a network with two subnets