cpufreq / intel_pstate: use lowest requested max performance

cpufreq / intel_pstate: use lowest requested max performance

commit d8f469e9cff3bc4a6317d923e9506be046aa7bdc upstream.

There are two ways that the maximum p-state can be clamped, via a
policy change and via the sysfs file.

The acpi-thermal driver adjusts the p-state policy in response to
thermal events.  These changes override the users settings at the
moment.

Use the lowest of the two requested values this ensures that we will
not exceed the requested pstate from either mechanism.

Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>