DisplayGLX: fix a SwapControl copy-paste error BUG=angleproject:1304 Change-Id: If0ec8682b1d519bc6460cd6ed82f42c4c1ceb952 Reviewed-on: https://chromium-review.googlesource.com/324930 Commit-Queue: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Tryjob-Request: Jamie Madill <jmadill@chromium.org> Tested-by: Corentin Wallez <cwallez@chromium.org>