kstyle: Fix class name to fix indeterminate progress bars animations
The Breeze implementation is older than qqc2-desktop-style framework, and historically it used to use different base class. Times has changed, along with base classes; but Breeze code did not -- instead the problem was workarounded on a org.kde.desktop side first with a dummy Timer that called updateItem(), then through more sophisticated QtQuick Animations types (which delivered smoother results thanks to being bound to refresh rate of a screen).
While this patch fixes the problem, it seems like a better solution should be possible or more cleanup opportunities are available:
- no other breeze animations invoke methods through QMetaObject system;
- why and how an object would be something other than KQuickStyleItem?