Ahaggar: add support to walk TREE_VEC nodes

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: walk TREE_VEC nodes

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: Nop for OFFSET_TYPE nodes

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: add more types to support

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>