crypto: qat - add get_svc_slice_cnt() in device data structure

Enhance the adf_hw_device_data structure by introducing a new callback
function get_svc_slice_cnt(), which provides a mechanism to query the
total number of accelerator available on the device for a specific
service.

Implement adf_gen4_get_svc_slice_cnt() for QAT GEN4 devices to support this
new interface. This function returns the total accelerator count for a
specific service.

Co-developed-by: George Abraham P <george.abraham.p@intel.com>
Signed-off-by: George Abraham P <george.abraham.p@intel.com>
Signed-off-by: Suman Kumar Chakraborty <suman.kumar.chakraborty@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>