dccp: Replace magic CCID-specific numbers by symbolic constants

The constants DCCPO_{MIN,MAX}_CCID_SPECIFIC are nowhere used in the code, but
instead for the CCID-specific options numbers are used.

This patch unifies the use of CCID-specific option numbers, by adding symbolic
names reflecting the definitions in RFC 4340, 10.3.

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

diff --cc include/linux/dccp.h
Simple merge

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