Drop unnecessary v2 namespace qualifications

Change-Id: I6358bac6860ca8f2e9cdbd00bb2a929e3af5b2da
diff --git a/tests/unit/security/validation-policy-config.t.cpp b/tests/unit/security/validation-policy-config.t.cpp
index 7b5fc56..dcd7cb8 100644
--- a/tests/unit/security/validation-policy-config.t.cpp
+++ b/tests/unit/security/validation-policy-config.t.cpp
@@ -37,7 +37,7 @@
 namespace tests {
 
 using namespace ndn::tests;
-using namespace ndn::security::v2::tests;
+using namespace ndn::security::tests;
 
 BOOST_AUTO_TEST_SUITE(Security)
 BOOST_AUTO_TEST_SUITE(TestValidationPolicyConfig)