msc/BSC_ConnectionHandler: fix early return in f_mm_ciph_geran()

In [1] I forgot to invert an if statement.  This regression caused
most of GERAN specific test cases to fail due to "Tguard timeout".

Change-Id: I8cbaff00abfd9eb252dc3011df848e2e24fe5a1e
Fixes: [1] Ib7ebe8fd675295beb02cadebb19d8465dffeb732
Related: OS#5333

msc/BSC_ConnectionHandler.ttcn

@@ -619,7 +619,7 @@ private function f_mm_ciph_geran() runs on BSC_ConnHdlr
 	var OCT1 a5_perm_alg;
 	var PDU_BSSAP pdu;
 
-	if (g_pars.net.expect_ciph) {
+	if (not g_pars.net.expect_ciph) {
 		/* There is nothing to do */
 		return;
 	}