msc: Accept optional f_init_handler() argument for Tguard

Some tests may want an extended guard timer as they're waiting for
some particularly slow events.  They can override the default now.

Change-Id: Iee6f50559a8fe45c7655b9f41e7fa163199b39a6
diff --git a/msc_tests/MSC_Tests.ttcn b/msc_tests/MSC_Tests.ttcn
index 2f85ab4..2e9176f 100644
--- a/msc_tests/MSC_Tests.ttcn
+++ b/msc_tests/MSC_Tests.ttcn
@@ -1406,7 +1406,7 @@
 
 /* Test MT Call T310 timer */
 private function f_tc_mt_t310(charstring id, BSC_ConnHdlrPars pars) runs on BSC_ConnHdlr {
-	f_init_handler(pars);
+	f_init_handler(pars, 200.0);
 	var CallParameters cpars := valueof(t_CallParams('123456'H, 0));
 	var MNCC_PDU mncc;
 	var MgcpCommand mgcp_cmd;