spirv: Make vtn_case a vtn_cf_node

Cherry-pick'd from 255aacbec14c2d11d7756ec94b95244165120ff6

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3820>
Change-Id: I6d095387e07bea82329011708dd1b44eaca262ba
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/mesa/+/403194
Reviewed-by: John Bauman <jbauman@google.com>
2 files changed