resmim: Adjust TC_createMapping_busySlot to current bankd code

Since osmo-remsim Change-Id I83e319d22896b881c0d882542842f500075aa546
createMapping will overwrite any existing mappings that may already
exist for that bank-slot.  We need to adjust our test expectations
accordingly.

Change-Id: Ia8de9edd7edb0437cd783b7d045571ff69820c42
Related: OS#4278
diff --git a/remsim/RemsimBankd_Tests.ttcn b/remsim/RemsimBankd_Tests.ttcn
index 4e87024..e86dc16 100644
--- a/remsim/RemsimBankd_Tests.ttcn
+++ b/remsim/RemsimBankd_Tests.ttcn
@@ -95,8 +95,10 @@
 	f_rspro_srv_reset_state(ok);
 	var BankSlot bs := { bankId := mp_bank_id, slotNr := 0 };
 	var ClientSlot cs := { clientId := 23, slotNr := 42 };
+	/* create the mapping the first time */
 	f_rspro_srv_create_slotmap(cs, bs);
-	f_rspro_srv_create_slotmap(cs, bs, exp_res := illegalSlotId);
+	/* re-create the mapping a second time */
+	f_rspro_srv_create_slotmap(cs, bs);
 	Misc_Helpers.f_shutdown(__BFILE__, __LINE__, pass);
 }