vkr: fix some null dereferences

We could also let the decoder check for them because vk.xml has
"optional" attribute that is used to specify whether a pointer can be
NULL or not.  For now, do it manually.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-by: Yiwei Zhang <zzyiwei@chromium.org>
1 file changed