Fix reuse of $link in report controller

Summary: $link gets reused later in the function, use a different variable name to avoid broken nonsense.

Test Plan: Clicked users/projects links.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, epriestley

Maniphest Tasks: T1038

Differential Revision: https://secure.phabricator.com/D2003