在任意输入框按回车就触发 OnSearchClick，改动如下：

<el-form
  :model="mFilterForm"
  :inline="true"
  @submit.prevent="OnSearchClick"
>
  <el-row>
    <el-form-item label="物料代码">
      <el-input v-model="mFilterForm.code" clearable style="width: 200px;" />
    </el-form-item>

    <el-form-item label="型号">
      <el-input v-model="mFilterForm.external_pn" clearable style="width: 200px;" />
    </el-form-item>

    <el-form-item label="描述">
      <el-input v-model="mFilterForm.summary" clearable style="width: 200px;" />
    </el-form-item>

    <el-form-item>
      <el-button 
        type="primary" 
        :icon="Search"
        native-type="submit"
        round
      >
        搜索
      </el-button>
    </el-form-item>
  </el-row>
</el-form>