Acknowledge link is clickable without any permission to update the problem

Steps to reproduce:

1. Create some problem events
2. Create user role and user
3. Remove all access for problem event update in user role:
   Add problem comments
   Change severity
   Acknowledge problems
   Suppress problems
   Close problems
4. Login as user with this role
5. Open Problems page
6. Click on "No" in Ack column

Result:
"No" is clickable, message in popup "Access denied"
Expected:
"No" or "Yes" is not clickable in the Ack column.