Documentation: qat: update debugfs-driver-qat_telemetry for GEN6 devices

Expands telemetry documentation for supporting QAT GEN6 device. Introduces
new parameters to capture compression, decompression slice utilization and
execution count.

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: Vijay Sundar Selvamani <vijay.sundar.selvamani@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>