i915_gem: Convert kmem_cache_alloc(...GFP_ZERO) to kmem_cache_zalloc

The helper exists, might as well use it instead of __GFP_ZERO.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -212,7 +212,7 @@ i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
 void *i915_gem_object_alloc(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	return kmem_cache_alloc(dev_priv->slab, GFP_KERNEL | __GFP_ZERO);
+	return kmem_cache_zalloc(dev_priv->slab, GFP_KERNEL);
 }
 
 void i915_gem_object_free(struct drm_i915_gem_object *obj)