nat: Fix copy and paste in the test code

The test didn't test that the access-list has been properly
removed. Fix the test to only remove the list once and verify
that it is gone.
diff --git a/openbsc/tests/ctrl_test_runner.py b/openbsc/tests/ctrl_test_runner.py
index 3238a1b..df2e66c 100644
--- a/openbsc/tests/ctrl_test_runner.py
+++ b/openbsc/tests/ctrl_test_runner.py
@@ -521,8 +521,8 @@
         self.assertEquals(r['var'], 'net')
         self.assertEquals(r['value'], None)
 
-        r = self.do_set('net.0.bsc_cfg.0.no-access-list-name', '1')
-        self.assertEquals(r['mtype'], 'SET_REPLY')
+        r = self.do_get('net.0.bsc_cfg.0.access-list-name')
+        self.assertEquals(r['mtype'], 'GET_REPLY')
         self.assertEquals(r['var'], 'net')
         self.assertEquals(r['value'], None)