drm: rcar-du: Don't initialize event->pipe field

The field is set by drm_send_vblank_event(), there's no need to
preinitialize it.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

drivers/gpu/drm/rcar-du/rcar_du_crtc.c

@@ -486,8 +486,6 @@ static void rcar_du_crtc_atomic_begin(struct drm_crtc *crtc)
 	unsigned long flags;
 
 	if (event) {
-		event->pipe = rcrtc->index;
-
 		WARN_ON(drm_crtc_vblank_get(crtc) != 0);
 
 		spin_lock_irqsave(&dev->event_lock, flags);