epdg: Remove unneeded register by message

Since recently GTP2 Emulation got improved routing, and it should simply
match by the already registered imsi.

Change-Id: I410242d6597db10b97edf72b92e749db28520c39
diff --git a/epdg/EPDG_Tests.ttcn b/epdg/EPDG_Tests.ttcn
index 60e0d1c..353c738 100644
--- a/epdg/EPDG_Tests.ttcn
+++ b/epdg/EPDG_Tests.ttcn
@@ -440,7 +440,6 @@
 	}
 }
 private function f_GTP2C_CreateSession_success() runs on EPDG_ConnHdlr {
-	f_gtp2_register_udmsg('20'O);
 	as_GTP2C_CreateSession_success();
 }