Create table didn't check the foreign key referenced column length

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)
```
mysql> create table t1(a varchar(222), index(a));
Query OK, 0 rows affected (0.06 sec)

mysql> create table t2(a varchar(2), index(a), constraint fk foreign key(a) references t1(a) on delete restrict);
Query OK, 0 rows affected (0.06 sec)
```

### 2. What did you expect to see? (Required)
The `varchar` length is not equal, table `t2` should't be created success

### 3. What did you see instead (Required)
Table `t2` can be created success
### 4. What is your TiDB version? (Required)
master