dleyna: Do not use format constant
dleyna: Do not use format constant

Make life easier for translators.

https://bugzilla.gnome.org/show_bug.cgi?id=732016

MathieuDuponchelle/grilo-plugins,MathieuDuponchelle/grilo-plugins,GNOME/grilo-plugins,jasuarez/grilo-plugins,MikePetullo/grilo-plugins,MathieuDuponchelle/grilo-plugins,jasuarez/grilo-plugins,MikePetullo/grilo-plugins,grilofw/grilo-plugins,MikePetullo/grilo-plugins,GNOME/grilo-plugins,grilofw/grilo-plugins,MathieuDuponchelle/grilo-plugins