crypto: qat - allow detection of dc capabilities for 4xxx

Add logic to allow the detection of data compression capabilities for
4xxx devices.
The capability detection logic has been refactored to separate the
crypto capabilities from the compression ones.

This patch is not updating the returned capability mask as, up to now,
4xxx devices are configured only to handle crypto operations.

Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Marco Chiappero <marco.chiappero@intel.com>
Reviewed-by: Fiona Trahe <fiona.trahe@intel.com>
Reviewed-by: Marco Chiappero <marco.chiappero@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>