crypto: qat - expose device config through sysfs for 4xxx

qat_4xxx devices can be configured to allow either crypto or compression
operations. At the moment, devices are configured statically according to
the following rule:
- odd numbered devices assigned to compression services
- even numbered devices assigned to crypto services

Expose the sysfs attribute /sys/bus/pci/devices/<BDF>/qat/cfg_services
to allow to detect the configuration of a device and to change it.

The `cfg_service` attribute is only exposed for qat_4xxx devices and it
is limited to two configurations: (1) "sym;asym" for crypto services and
"dc" for compression services.

Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Co-developed-by: Tomasz Kowallik <tomaszx.kowalik@intel.com>
Signed-off-by: Tomasz Kowallik <tomaszx.kowalik@intel.com>
Reviewed-by: Adam Guerin <adam.guerin@intel.com>
Reviewed-by: Fiona Trahe <fiona.trahe@intel.com>
Reviewed-by: Wojciech Ziemba <wojciech.ziemba@intel.com>
Reviewed-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>