bankd: initialize bank_id/slot_nr to 0xffff for unmapped workers

Otherwise the loop for SIGMAPDEL delivery code will match any
unused worker for bank_id=0/slot_nr=0, which is not what we want.

This also makes repeated RemsimBankd_Tests.TC_removeMapping_connected
runs work reliably.

Change-Id: I6976eb96feae6a3b66bacf787e436a2df29f9ce0
diff --git a/src/bankd/bankd_main.c b/src/bankd/bankd_main.c
index 94227e3..09a9e1d 100644
--- a/src/bankd/bankd_main.c
+++ b/src/bankd/bankd_main.c
@@ -411,6 +411,8 @@
 {
 	LOGW(g_worker, "SIGMAPDEL received: Main thread informs us our map is gone\n");
 	OSMO_ASSERT(sig == SIGMAPDEL);
+	g_worker->slot.bank_id = 0xffff;
+	g_worker->slot.slot_nr = 0xffff;
 	worker_set_state(g_worker, BW_ST_CONN_CLIENT_UNMAPPED);
 }
 
@@ -852,6 +854,9 @@
 	/* push cleanup helper */
 	pthread_cleanup_push(&worker_cleanup, g_worker);
 
+	g_worker->slot.bank_id = 0xffff;
+	g_worker->slot.slot_nr = 0xffff;
+
 	/* we continuously perform the same loop here, recycling the worker thread
 	 * once the client connection is gone or we have some trouble with the card/reader */
 	while (1) {