Use Q_ENUM instead of obsoleted Q_ENUMS

It fixes the following warning:
Use Q_ENUM instead of Q_ENUMS [clazy-qenums]

In addition, it amends 8588cf268f
where WidgetStyle got removed.

Change-Id: I4d72dd762a2f18ba8886360b3581b4ef19bf4c5e
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/detailswidget.h

@@ -44,7 +44,6 @@ class QTCREATOR_UTILS_EXPORT DetailsWidget : public QWidget
     Q_PROPERTY(bool useCheckBox READ useCheckBox WRITE setUseCheckBox DESIGNABLE true)
     Q_PROPERTY(bool checked READ isChecked WRITE setChecked DESIGNABLE true)
     Q_PROPERTY(State state READ state WRITE setState)
-    Q_ENUMS(State)
 
 public:
     enum State {
@@ -53,6 +52,7 @@ public:
         NoSummary,
         OnlySummary
     };
+    Q_ENUM(State)
 
     explicit DetailsWidget(QWidget *parent = nullptr);
     ~DetailsWidget() override;