drm: read breadcrumb in IRQ handler

From: Keith Whitwell <keithw@tungstengraphics.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>

drivers/char/drm/i915_irq.c

@@ -53,6 +53,8 @@ irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)
 
 	I915_WRITE16(I915REG_INT_IDENTITY_R, temp);
 
+	dev_priv->sarea_priv->last_dispatch = READ_BREADCRUMB(dev_priv);
+
 	if (temp & USER_INT_FLAG)
 		DRM_WAKEUP(&dev_priv->irq_queue);