Doc: Fix QCH filter attributes for Qt Quick Controls/Styles

Fix typos in filter attibutes, preventing filtering from working in
Assistant.

Task-number: QTBUG-31796
Change-Id: I21c91b43881cd73ae7df4203922085e7c9f93e8f
Reviewed-by: Caroline Chao <caroline.chao@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>