Remove uneeded default args for plugin constructors

We never call this constructor manually

kcm/kcm.h

@@ -40,7 +40,7 @@ class ScreenLockerKcm : public KQuickAddons::ManagedConfigModule
 {
     Q_OBJECT
 public:
-    explicit ScreenLockerKcm(QObject *parent = nullptr, const KPluginMetaData &data = {}, const QVariantList &args = QVariantList());
+    explicit ScreenLockerKcm(QObject *parent, const KPluginMetaData &data, const QVariantList &args);
 
     Q_PROPERTY(KScreenSaverSettings *settings READ settings CONSTANT)
     Q_PROPERTY(KConfigPropertyMap *wallpaperConfiguration READ wallpaperConfiguration NOTIFY currentWallpaperChanged)

kcm/kscreenlockerdata.h

@@ -31,7 +31,7 @@ class KScreenLockerData : public KCModuleData
     Q_OBJECT
 
 public:
-    explicit KScreenLockerData(QObject *parent = nullptr, const QVariantList &args = QVariantList());
+    explicit KScreenLockerData(QObject *parent, const QVariantList &args);
 
     bool isDefaults() const override;