dccp ccid-2: Remove old infrastructure

This removes
 * functions for which updates have been provided in the preceding patches and
 * the @av_vec_len field - it is no longer necessary since the buffer length is
   now always computed dynamically.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

diff --cc net/dccp/ackvec.c
Simple merge

diff --cc net/dccp/ackvec.h
Simple merge