Use Locale::name() instead of Locale::bcp47Name()

Summary:
bcp47Name() is encoded like "en-US" the dictionary name on the other hand
is "en_US" so lets use name().

Reviewers: dfaure, mlaurent, kfunk, vkrause

Reviewed By: dfaure

Subscribers: apol, Frameworks

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D10741