baloo-widgets: Apply coding style to filemetadataprovider
Summary:
Prepare fixing bug 388583
CCBUG: 388583
Test Plan:
Visual inspection
make test
Reviewers: elvisangelaccio, smithjd, ngraham, vhanda, Dolphin
Reviewed By: elvisangelaccio
Differential Revision: https://phabricator.kde.org/D10143