sgsn/SGSN_Tests.cfg: also run Iu tests

Change-Id: Ia6ee4b2776cfbb9295334617d8c201c21d1663f7
diff --git a/sgsn/SGSN_Tests.cfg b/sgsn/SGSN_Tests.cfg
index 566c804..26cee47 100644
--- a/sgsn/SGSN_Tests.cfg
+++ b/sgsn/SGSN_Tests.cfg
@@ -41,3 +41,4 @@
 
 [EXECUTE]
 SGSN_Tests.control
+SGSN_Tests_Iu.control