crypto: qat - add measure clock frequency

The QAT hardware does not expose a mechanism to report its clock
frequency. This is required to implement the Heartbeat feature.

Add a clock measuring algorithm that estimates the frequency by
comparing the internal timestamp counter incremented by the firmware
with the time measured by the kernel.
The frequency value is only used internally and not exposed to
the user.

Signed-off-by: Damian Muszynski <damian.muszynski@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>