cpufreq: intel_pstate: Remove unneeded variable

It should have been removed with commit d1b68485
("cpufreq / intel_pstate: Optimize intel_pstate_set_policy")

Signed-off-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>