cpufreq: intel_pstate: Disable interrupts during MSRs reading
cpufreq: intel_pstate: Disable interrupts during MSRs reading

According to Intel 64 and IA-32 Architectures SDM, Volume 3,
Chapter 14.2, "Software needs to exercise care to avoid delays
between the two RDMSRs (for example interrupts)".

So, disable interrupts during reading MSRs IA32_APERF and IA32_MPERF.
This should increase the accuracy of the calculations.

Signed-off-by: Stratos Karafotis <7d26b35203412f18a7dea4f8e1db1a75b1c5b706@semaphore.gr>
Signed-off-by: Dirk Brandewie <90b1bc8a6ba9849b6d077cb338e79c4550ccbc5f@intel.com>
Signed-off-by: Rafael J. Wysocki <27ffc44a8ec6a212fba98cfc3246c6ce8ab131e0@intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs