Remove the TextFix workaround for QML text mouse handling bug.

Summary:
Cf.: https://codereview.qt-project.org/#/c/113758/

This was merged into Qt v5.6.2 and this branch thus doesn't
support Qt v5.6 for the time being.

The textFix call in the onCompleted handler now shows up as one
of the remaining hotspots in the delegate.

Reviewers: broulik, Plasma

Reviewed By: broulik, Plasma

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D4345