I'm unable to set default value for multi select inside form.

**Use Case:**
I have created a react component that renders a select with some default props that I need in every form.
Now I want to set default value for that select from the `defaultValue` prop of select instead of passing `initialValues` to every form.

My react component looks like:

```
import React, { Component } from 'react';
import { Form, Select } from 'antd';

class FormSelect extends Component {
  render() {
    const {name, label, rules, onSelect, disabled, options, mode} = this.props;

    let defaultValue;
    if (mode === 'tags' || mode === 'multiple'){
      defaultValue = [];
    }

    return (
      <Form.Item
        hasFeedback
        name={name}
        label={label}
        rules={rules}
      >
        <Select
          showSearch
          mode={mode}
          tokenSeparators={[',']}
          defaultValue={defaultValue}
          onSelect={onSelect}
          disabled={disabled}
        >
          {
            options.map((op) => (
              <Select.Option key={op.value} value={op.value} label={op.label}>
                {op.label}
              </Select.Option>
            ))
          }
        </Select>
      </Form.Item>
    );
  }
}
export default FormSelect;

```

The problem is when I set the `defaultValue` prop of select the value is shown in UI but when the form is submitted the defaultValue is ignored and value of select field remains `undefined`