Fix warning about unused variable

QPoint has no side-effects so it's safe to remove.

 main.cpp:214:12: warning: unused variable 'gradCenter' [-Wunused-variable]

Change-Id: I27b55fdf514247549455fffd14b179b3a6a08617
Reviewed-by: Johan Helsing <johan.helsing@qt.io>

src/plugins/platforms/wayland/plugins/decorations/bradient/main.cpp

@@ -211,7 +211,6 @@ void QWaylandBradientDecoration::paint(QPaintDevice *device)
     p.setRenderHint(QPainter::Antialiasing);
 
     // Title bar
-    QPoint gradCenter(top.center()+ QPoint(30, 60));
     QLinearGradient grad(top.topLeft(), top.bottomLeft());
     QColor base(m_backgroundColor);
     grad.setColorAt(0, base.lighter(100));