cpufreq: Remove (now) unused 'last_cpu' from struct cpufreq_policy

'last_cpu' was used only from cpufreq-stats and isn't used anymore. Get rid of
it.
Reviewed-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

@@ -1086,10 +1086,7 @@ static int update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu,
 	}
 
 	down_write(&policy->rwsem);
-
-	policy->last_cpu = policy->cpu;
 	policy->cpu = cpu;
-
 	up_write(&policy->rwsem);
 
 	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,

include/linux/cpufreq.h

@@ -66,8 +66,6 @@ struct cpufreq_policy {
 	unsigned int		shared_type; /* ACPI: ANY or ALL affected CPUs
 						should set cpufreq */
 	unsigned int		cpu;    /* cpu nr of CPU managing this policy */
-	unsigned int		last_cpu; /* cpu nr of previous CPU that managed
-					   * this policy */
 	struct clk		*clk;
 	struct cpufreq_cpuinfo	cpuinfo;/* see above */