Include disptype and transport in dispatch hash key

Include disptype and transport in dispatch hash key

Move disptype and transport into dispatch_hash() and dispatch_match()
so that the match function is the single source of truth for whether
two TCP dispatches are interchangeable.  This replaces the post-loop
disptype filter in dispatch_gettcp() and makes the disptype field in
struct dispatch_key actually used.

(cherry picked from commit 46547966839926313abdb4f4de57a8e94a64f0c0)