cpufreq: intel_pstate: Remove unused member name of cpudata

Although, a value is assigned to member name of struct cpudata,
it is never used.

We can safely remove it.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>