drm: i915: drop null test before destroy functions

Remove unneeded NULL test.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@ expression x; @@
-if (x != NULL)
  \(kmem_cache_destroy\|mempool_destroy\|dma_pool_destroy\)(x);
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_dma.c

@@ -1074,11 +1074,8 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 put_bridge:
 	pci_dev_put(dev_priv->bridge_dev);
 free_priv:
-	if (dev_priv->requests)
 	kmem_cache_destroy(dev_priv->requests);
-	if (dev_priv->vmas)
 	kmem_cache_destroy(dev_priv->vmas);
-	if (dev_priv->objects)
 	kmem_cache_destroy(dev_priv->objects);
 	kfree(dev_priv);
 	return ret;
@@ -1170,13 +1167,9 @@ int i915_driver_unload(struct drm_device *dev)
 	if (dev_priv->regs != NULL)
 		pci_iounmap(dev->pdev, dev_priv->regs);
 
-	if (dev_priv->requests)
 	kmem_cache_destroy(dev_priv->requests);
-	if (dev_priv->vmas)
 	kmem_cache_destroy(dev_priv->vmas);
-	if (dev_priv->objects)
 	kmem_cache_destroy(dev_priv->objects);
-
 	pci_dev_put(dev_priv->bridge_dev);
 	kfree(dev_priv);