modules: set: really remove persistent keepalive

_modules/wireguard.py

         if not peer:
             return 'If endpoint is given, peer must also be given'
         s = '%s endpoint %s' % (s, endpoint)
-    if persistent_keepalive:
+    if persistent_keepalive is not None:
         if not peer:
             return 'If persistent_keepalive is given, peer must also be given'
         s = '%s persistent-keepalive %s' % (s, persistent_keepalive)

_states/wireguard.py

 
     show = __salt__['wg.show'](name, hide_keys=False)
 
-    if int(show.get('listening port', 0)) != int(listen_port):
+    if listen_port and int(show.get('listening port', 0)) != int(listen_port):
         __salt__['wg.set'](name, listen_port=listen_port)
         ret['changes']['listening port'] = dict(
                 old=show.get('listening port', 0),
         ret['changes']['endpoint'] = dict(
                 old=show.get('endpoint'), new=endpoint)
 
-    if persistent_keepalive and show.get('persistent keepalive', '').startswith('every %s second' % (persistent_keepalive,)):
+    if persistent_keepalive and not show.get('persistent keepalive', '').startswith('every %s second' % (persistent_keepalive,)):
         __salt__['wg.set'](interface, peer=name,
                 persistent_keepalive=persistent_keepalive)
         ret['changes']['persistent keepalive'] = 'persistent keepalive changed.'