drm/vgem: switch to postclose

I didn't spot anything that would require ordering here (well not
anywhere else either), and I'm trying to unify at least modern drivers
on one close hook.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NSean Paul <seanpaul@chromium.org>
Reviewed-by: NLiviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170308141257.12119-18-daniel.vetter@ffwll.ch

drivers/gpu/drm/vgem/vgem_drv.c

@@ -103,7 +103,7 @@ static int vgem_open(struct drm_device *dev, struct drm_file *file)
 	return 0;
 }
 
-static void vgem_preclose(struct drm_device *dev, struct drm_file *file)
+static void vgem_postclose(struct drm_device *dev, struct drm_file *file)
 {
 	struct vgem_file *vfile = file->driver_priv;
 
@@ -302,7 +302,7 @@ static int vgem_prime_mmap(struct drm_gem_object *obj,
 static struct drm_driver vgem_driver = {
 	.driver_features		= DRIVER_GEM | DRIVER_PRIME,
 	.open				= vgem_open,
-	.preclose			= vgem_preclose,
+	.postclose			= vgem_postclose,
 	.gem_free_object_unlocked	= vgem_gem_free_object,
 	.gem_vm_ops			= &vgem_gem_vm_ops,
 	.ioctls				= vgem_ioctls,