The ZLIB format (RFC 1950) is made of deflate compressed data surrounded
by a header and a footer. The QAT accelerators support only the deflate
algorithm, therefore the header and the footer need to be inserted in
software.

This adds logic in the QAT driver to support the ZLIB format. In
particular:
  * Generalize the function qat_comp_alg_compress_decompress() to allow
    skipping an initial region (header) of the source and/or destination
    scatter lists.
  * Add logic to register the qat_zlib_deflate algorithm into the acomp
    framework.
  * For ZLIB compression, skip the initial portion of the destination
    buffer before sending the job to the QAT accelerator and insert the
    ZLIB header and footer in the callback, after the QAT request has
    been processed.
  * For ZLIB decompression, parse the header in the input buffer
    provided by the user and verify its validity before attempting the
    decompression of the buffer with QAT. Then submit the buffer to QAT
    for decompression. In the callback verify the correctness of the
    footer by comparing the value of the ADLER produced by QAT with the
    one in the destination buffer.
Signed-off-by: Lucas Segarra Fernandez <lucas.segarra.fernandez@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>