Some properties of El input in [bug report] render function are invalid

### Element UI version
2.14.1

### OS/Browsers version
谷歌版本 72.0.3626.119（正式版本） （64 位）

### Vue version
2.6.11

### Reproduction Link
https://elementui.github.io/issue-generator/#/zh-CN/暂无

### Steps to reproduce
render (h) {
return h('el-form-item', {
props: {
label: this.label,
prop: this.prop
},
style: {},
on: {}
},
[h('el-input', {
attr: {},
props: {
type: this.type,
value: this.value,
clearable: this.clearable,
size: this.size,
placeholder: this.placeholder,
},
domProps: {},
style: {},
'class': {
},
on: {
input: (v) => {
console.log(v)
this.$emit('upvalue', v)
}
}
},
[]
)]
)
}

### What is Expected?
placeholder 有值

### What is actually happening?
placeholder 不显示