[improvement] unify mixin name (#2795)

packages/datetime-picker/index.js

@@ -1,7 +1,13 @@
 import { use, range } from '../utils';
 import Picker from '../picker';
-import PickerMixin from '../mixins/picker';
-import { times, padZero, isValidDate, getTrueValue, getMonthEndDay } from './utils';
+import { PickerMixin } from '../mixins/picker';
+import {
+  times,
+  padZero,
+  isValidDate,
+  getTrueValue,
+  getMonthEndDay
+} from './utils';
 
 const [sfc, bem] = use('datetime-picker');
 const currentYear = new Date().getFullYear();
@@ -96,14 +102,21 @@ export default sfc({
         ];
       }
 
-      const { maxYear, maxDate, maxMonth, maxHour, maxMinute } = this.getBoundary(
-        'max',
-        this.innerValue
-      );
-      const { minYear, minDate, minMonth, minHour, minMinute } = this.getBoundary(
-        'min',
-        this.innerValue
-      );
+      const {
+        maxYear,
+        maxDate,
+        maxMonth,
+        maxHour,
+        maxMinute
+      } = this.getBoundary('max', this.innerValue);
+
+      const {
+        minYear,
+        minDate,
+        minMonth,
+        minHour,
+        minMinute
+      } = this.getBoundary('min', this.innerValue);
 
       const result = [
         {