crypto: scomp - add support for deflate rfc1950 (zlib)

Add scomp backend for zlib-deflate compression algorithm.
This backend outputs data using the format defined in rfc1950
(raw deflate surrounded by zlib header and footer).

Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>