[Bug Report] time-range value validation is wrong because it always uses the last value instead of the latest value

### Element UI version
2.15.6

### OS/Browsers version
Windows & MacOs / Chrome 95.0.4638.69

### Vue version
2.6.14

### Reproduction Link
https://codepen.io/donggua-c/pen/zYdPExM

### Steps to reproduce
1. Choose the minimum time【Like 7.00 am】
2. Choose a suitable maximum time (in order to better reproduce the problem)【Like 9.00 am】
3. Set the minimum time to exceed the maximum time【After 9.00 am】
4. Adjust the maximum time that after 9.00am
1. 选择最小时间【比如 7.00 am】
2. 选择一个合适的最大时间（以便更好的复现问题）【比如 9.00 am】
3. 将最小时间设置为超过最大的时间【大于 9.00 am】
4. 调整最大时间为 9.00 am 以后【比如 10.00 am】

### What is Expected?
When one time changes, the other time range should change its time limit synchronously. For the above example, disabled time range should after 10.00 am and the minimum value wasn't disabled currently.

当一项时间改变时，另一个时间范围应该同步改变其时间限制。以上面的例子来说，禁用的时间范围应该是在 10.00 am 之后并且当前最小值不应该是禁用状态

### What is actually happening?
When one time changes, the other time range does not change its time limit synchronously. For the above example, disabled time range will not changed and the minimum value still disabled.

当一项时间改变时，另一个时间范围并没有同步改变其时间限制。以上面的例子来说，禁用的时间范围没有变化并且最小时间依旧被禁用