drm: don't cast a pointer to pointer of list_head

The casting is safe only when the list_head member is the first member of
the structure.

Signed-off-by: Li Zefan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/char/drm/i915_irq.c

···
 
 	spin_lock_irqsave(&dev_priv->swaps_lock, irqflags);
 
-	list_add_tail((struct list_head *)vbl_swap, &dev_priv->vbl_swaps.head);
+	list_add_tail(&vbl_swap->head, &dev_priv->vbl_swaps.head);
 	dev_priv->swaps_pending++;
 
 	spin_unlock_irqrestore(&dev_priv->swaps_lock, irqflags);