drm: Change the return type of the unload hook to void

The integer returned by the unload hook is ignored by the drm core, so
let's make it void.

This patch was created using the following Coccinelle semantic script
(except for the declaration and comment in drm_drv.h):

Compile-tested only.

// <smpl>
@ get_name @
struct drm_driver drv;
identifier fn;
@@
drv.unload = fn;

@ replace_type @
identifier get_name.fn;
@@
- int
+ void
fn (...)
{
...
}

@ remove_return_param @
identifier get_name.fn;
@@
void fn (...)
{
<...
if (...)
return
- ...
;
...>
 }

@ drop_final_return @
identifier get_name.fn;
@@
void fn (...)
{
...

- return 0;
}
// </smpl>

Suggested-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Acked-by: Christian König <christian.koenig@amd.com>.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170106175731.29196-1-krisman@collabora.co.uk

drivers/gpu/drm/via/via_drv.h

@@ -134,7 +134,7 @@ extern int via_dma_blit_sync(struct drm_device *dev, void *data, struct drm_file
 extern int via_dma_blit(struct drm_device *dev, void *data, struct drm_file *file_priv);
 
 extern int via_driver_load(struct drm_device *dev, unsigned long chipset);
-extern int via_driver_unload(struct drm_device *dev);
+extern void via_driver_unload(struct drm_device *dev);
 
 extern int via_init_context(struct drm_device *dev, int context);
 extern int via_final_context(struct drm_device *dev, int context);

drivers/gpu/drm/via/via_map.c

@@ -116,13 +116,11 @@ int via_driver_load(struct drm_device *dev, unsigned long chipset)
 	return 0;
 }
 
-int via_driver_unload(struct drm_device *dev)
+void via_driver_unload(struct drm_device *dev)
 {
 	drm_via_private_t *dev_priv = dev->dev_private;
 
 	idr_destroy(&dev_priv->object_idr);
 
 	kfree(dev_priv);
-
-	return 0;
 }