core: Remove a redundant 'using' statement
core: Remove a redundant 'using' statement

jku/rygel,Tarnyko/rygel,luisbg/rygel,jku/rygel,GNOME/rygel,Pelagicore/Media-Manager-Rygel-patched,Tarnyko/rygel,GNOME/rygel,GNOME/rygel,Pelagicore/Media-Manager-Rygel-patched,Pelagicore/Media-Manager-Rygel-patched