drm/virtio: fix memory leak in virtio_gpu_cleanup_object()

Before setting shmem->pages to NULL, kfree() should
be called.

Signed-off-by: Xin He <[e-mail]>
Reviewed-by: Qi Liu <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Gerd Hoffmann <[e-mail]>

drivers/gpu/drm/virtio/virtgpu_object.c

···
 			}
 
 			sg_free_table(shmem->pages);
+			kfree(shmem->pages);
 			shmem->pages = NULL;
 			drm_gem_shmem_unpin(&bo->base.base);
 		}