QStyle debug helpers: refactor dead code

... or compilers complain about the second, unreachable return.

Change-Id: Ic89361859fcf5cf33a57de0c803526702fa831b8
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>

src/widgets/styles/qstyle.cpp

@@ -2368,8 +2368,8 @@ QDebug operator<<(QDebug debug, QStyle::State state)
     return operator<< <QStyle::StateFlag>(debug, state);
 #    else
     Q_UNUSED(state);
-#    endif
     return debug;
+#    endif
 }
 #  endif // !QT_NO_DEBUG_STREAM
 #endif // QT_VERSION < QT_VERSION_CHECK(6,0,0)