dccp: remove unused macros

Remove macros which have been unused since the initial implementation
(commit 7c657876b63cb1d8a2ec06f8fc6c37bb8412e66c, [DCCP]: Initial
 implementation from Tue Aug 9 20:14:34 2005 -0700).

Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Acked-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
1 file changed