Fix operator error in Pholio with PHP 7.1

Summary: Fixes T12166. We don't actually need this variable, so removing it.

Test Plan: Upload a new mock, edit a mock, view list of mocks.

Reviewers: epriestley, Mnkras, acs-ferreira

Reviewed By: epriestley, Mnkras, acs-ferreira

Subscribers: acs-ferreira, Korvin

Maniphest Tasks: T12166

Differential Revision: https://secure.phabricator.com/D17260