BattMon: fix example sketch compile error

libraries/AP_BattMonitor/examples/AP_BattMonitor_test/AP_BattMonitor_test.pde

@@ -41,7 +41,7 @@ void setup() {
 
     // initialise the battery monitor
     battery_mon.init();
-    battery_mon.set_monitoring(AP_BATT_MONITOR_VOLTAGE_AND_CURRENT);
+    battery_mon.set_monitoring(0, BattMonitor_TYPE_ANALOG_VOLTAGE_AND_CURRENT);
 
     hal.scheduler->delay(1000);
     timer = hal.scheduler->millis();