fix link to notes in merge request diff

Created by: skv-headless

http://localhost:3000/gitlabhq/gitlab-ci/merge_requests/1/diffs#note_316 scroll in such links doesn't work. It happens because on page there are 2 elements with id="note_316" in changes and discussion. Browser takes first for scroll. This solution works because changes loads without diffs so tag with id="note_316" just one. Diffs loads with discussions, but in this case diff tag would be first. It is dirty but working solution.