refactor(snack.vue): 修改：店内执行上报_零食陈列填报模式中_实际陈列形式支持清除功能

src/views/promotion/display_schedule/tabs/snack.vue

@@ -293,7 +293,8 @@
                     submitChange(row, col);
                   }}
                   disabled={!row[col.referenceKey]}
-                  placeholder="">
+                  placeholder=""
+                  clearable>
                   {col.options.map(item => (
                     <el-option
                       key={item.value}