SGSN: move TLLI unassignment into separate function

Change-Id: Ia4df145ab03ebcaad70a13601cff60c488a5de54
Related: OS#1582
diff --git a/openbsc/tests/sgsn/sgsn_test.c b/openbsc/tests/sgsn/sgsn_test.c
index f425c33..d568807 100644
--- a/openbsc/tests/sgsn/sgsn_test.c
+++ b/openbsc/tests/sgsn/sgsn_test.c
@@ -222,7 +222,7 @@
 	OSMO_ASSERT(count(gprs_llme_list()) == 1);
 
 	/* unassign which should delete it*/
-	gprs_llgmm_assign(lle->llme, lle->llme->tlli, 0xffffffff, GPRS_ALGO_GEA0, NULL);
+	gprs_llgmm_unassign(lle->llme);
 
 	/* Check that everything was cleaned up */
 	OSMO_ASSERT(count(gprs_llme_list()) == 0);