The list insertion operations were open coded at each location. Add helper functions which provide the semantics needed by the selfboot code in a single place. Change-Id: Ic757255e01934b499def839131c257bde9d0cc93 Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://review.coreboot.org/15601 Tested-by: build bot (Jenkins) Reviewed-by: Furquan Shaikh <furquan@google.com> Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Patrick Georgi <pgeorgi@google.com>