fix junos typo (#19648)

closes #19646

lib/ansible/modules/network/junos/junos_config.py

@@ -287,7 +287,7 @@ def load_config(module, result):
 def rollback_config(module, result):
     rollback = module.params['rollback']
 
-    kwargs = dict(comment=module.param['comment'],
+    kwargs = dict(comment=module.params['comment'],
                   commit=not module.check_mode)
 
     diff = module.connection.rollback_config(rollback, **kwargs)