The data structure |struct drm_gem_vram_object| and its helpers replace
|struct ast_bo|. It's the same implementation; except for the type names.

v4:
	* cleanups from checkpatch.pl
Signed-off-by: NThomas Zimmermann <tzimmermann@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20190508082630.15116-10-tzimmermann@suse.deSigned-off-by: NGerd Hoffmann <kraxel@redhat.com>