Steps to reproduce

1. **Create a forum with whole forum grading(points) and a grading guide 
2. Define at least two criteria
   1. one with a max points value of 30
   2. another with a max points value of 20
3. Enter the forum's grading panel interface
4. Grade a user with 40 points in the first criterion and 10 points in the second criterion
5. Click the save button
6. The grade will be saved fine even though the first criterion's max points value was violated

Current behavior

If a forum is configured for whole forum grading + grading guide, the individual criteria maximums are not being honored in the grading interface.

Criteria point values entered can exceed their max as long as the total points for the forum are not exceeded.

For instance if I have one criterion with a max value of 30 and another with a max value of 20, When I go to grade an individual user in the grading panel, I can enter a points value of 40 for the first criterion so long as I do not exceed 10 for the second one since that would exceed the combined total of 50. 

If I were to enter a grade of 11 points for the second criterion it will thrown an error since that would now exceed the combined maximum of 50(40 + 11 = 51).

Expected behavior

**Moodle should not allow you to exceed the max point values for each level as defined in the grading guide.

In the example as described above the value of 40 should not be accepted for a criterion that has a 30 point maximum.