修复银行分行信息可以输入空格的 bug review by sunkai

@@ -58,7 +58,8 @@ export default class BankCard extends Component {
             return
         }
 
-        if (!this.state.bankBranch) {
+        let bankBranch = this.state.bankBranch;
+        if (!bankBranch || !bankBranch.trim()) {
             this.setState({messageTips: '请输入分行/支行信息'});
             return
         }