[Bug Report] 全局设置ElementUI.Input['props'].clearable.default = true后，DatePicker组件上设置clearable为false不生效

[Li-DaDa]

Element UI version

2.15.6

OS/Browsers version

Win10/Chrome 83.0.4103.97

Vue version

2.6.11

Reproduction Link

https://codepen.io/Li-DaDa/pen/NWmmyRy

Steps to reproduce

先全局设置ElementUI.Input['props'].clearable.default = true，然后在ElDatePicker组件设置clearable为false，此时不生效了

What is Expected?

ElDatePicker组件上单独设置的属性优先级应该更高

What is actually happening?

全局设置的Input属性后ElDatePicker设置clearable无效