arch: replace open computation in jive_load_node_normal_form_cast
arch: replace open computation in jive_load_node_normal_form_cast

Replace open computation in jive_load_node_normal_form_cast with
convenience function.

Signed-off-by: Helge Bahmann <c5618920f622561f9c0ec5c42219c4c08180149f@chaoticmind.net>

phate/jive,phate/jive,phate/jive