Renamed the private part of the namespace to QTlsPrivate.
Fixes: QTBUG-91531
Change-Id: Id2d9c458d8d958b35e437eee42889177dad0a7a7
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
(cherry picked from commit e4efa00c72c7011f4e5c27722c2a522b30274610)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>