zlib: clean up some dead code

zlib: clean up some dead code

Cleanup unused `if 0'-ed functions, which have been dead since 2006
(commits 87c2ce3b9305 ("lib/zlib*: cleanups") by Adrian Bunk and
4f3865fb57a0 ("zlib_inflate: Upgrade library code to a recent version")
by Richard Purdie):

 - zlib_deflateSetDictionary
 - zlib_deflateParams
 - zlib_deflateCopy
 - zlib_inflateSync
 - zlib_syncsearch
 - zlib_inflateSetDictionary
 - zlib_inflatePrime

Signed-off-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>