[Bug Report] Multiple-select does not display label with default value when value is an object array and options is empty

### Element UI version
2.15.7

### OS/Browsers version
macOS 11.5.2 / chrome 96.0.4664.110

### Vue version
2.6.14

### Reproduction Link
https://codepen.io/taoshowa/pen/KKygREK

### Steps to reproduce
当value初始设置的对象数组有数据，options无值或有值但不包含value中的数据时，input框中的label无法正常显示。

When the object array initially set by value has data and options has no value or has a value but does not contain the data in value, the label in the input box does not display properly.

### What is Expected?
正常显示。

Normal display.

### What is actually happening?
无法显示。

Cannot display.