Update commands to match the strings in pynx584 (#4623)

The command string don't match the ones pynx584. See source code:

https://github.com/kk7ds/pynx584/blob/master/nx584/api.py#L68

homeassistant/components/alarm_control_panel/nx584.py

@@ -117,11 +117,11 @@ class NX584Alarm(alarm.AlarmControlPanel):
 
     def alarm_arm_home(self, code=None):
         """Send arm home command."""
-        self._alarm.arm('home')
+        self._alarm.arm('stay')
 
     def alarm_arm_away(self, code=None):
         """Send arm away command."""
-        self._alarm.arm('auto')
+        self._alarm.arm('exit')
 
     def alarm_trigger(self, code=None):
         """Alarm trigger command."""