remove unused brackets

Author: AllenFang

src/BootstrapTable.js

@@ -200,7 +200,7 @@ class BootstrapTable extends Component {
       style: column.props.tdStyle
     };
 
-    if ((column).type !== TableHeaderColumn && React.isValidElement(column.props.children)) {
+    if (column.type !== TableHeaderColumn && React.isValidElement(column.props.children)) {
       columnDescription = {
         ...columnDescription,
         ...this.getColumnDescription(React.Children.only(column.props.children))