fixing logging action

packages/grafana-ui/src/components/ValueMappingsEditor/ValueMappingsEditor.story.tsx

@@ -6,12 +6,5 @@ import { ValueMappingsEditor } from './ValueMappingsEditor';
 const ValueMappingsEditorStories = storiesOf('UI/ValueMappingsEditor', module);
 
 ValueMappingsEditorStories.add('default', () => {
-  return (
-    <ValueMappingsEditor
-      valueMappings={[]}
-      onChange={() => {
-        action('Mapping changed');
-      }}
-    />
-  );
+  return <ValueMappingsEditor valueMappings={[]} onChange={action('Mapping changed')} />;
 });