Fixup OF 1.4 input file

Reviewer: trivial

 - Add "_t" suffix to list members
 - Add "== ?" syntax to discriminators.
 - Add inheritance.
 - Use of_octets_t for opaque data.
 - Remove _header suffix from inheritance roots.
 - Change 'ofp_' to 'of_' in struct definitions.

CC @alshabib