DEBUG: cpufreq: fix cpu_capacity tracing build for non-smp systems

cpu curr capacity can only be traced for SMP systems. Non-SMP builds
will fail with:

drivers/cpufreq/cpufreq.c: In function ‘cpufreq_freq_transition_begin’:
drivers/cpufreq/cpufreq.c:438:22: error: implicit declaration of function ‘capacity_curr_of’ [-Werror=implicit-function-declaration]
   trace_cpu_capacity(capacity_curr_of(cpu), cpu);
                      ^

Fixes: Change-Id: Icd0930d11068fcb7d2b6a9a48e7ed974904e1081
       ("DEBUG: sched,cpufreq: add cpu_capacity change tracepoint")
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
[jstultz: Cherry-picked from common/android-3.18]
Signed-off-by: John Stultz <john.stultz@linaro.org>

drivers/cpufreq/cpufreq.c

@@ -29,7 +29,9 @@
 #include <linux/suspend.h>
 #include <linux/syscore_ops.h>
 #include <linux/tick.h>
+#ifdef CONFIG_SMP
 #include <linux/sched.h>
+#endif
 #include <trace/events/power.h>
 
 static LIST_HEAD(cpufreq_policy_list);
@@ -474,7 +476,9 @@ static void cpufreq_notify_post_transition(struct cpufreq_policy *policy,
 void cpufreq_freq_transition_begin(struct cpufreq_policy *policy,
 		struct cpufreq_freqs *freqs)
 {
+#ifdef CONFIG_SMP
 	int cpu;
+#endif
 
 	/*
 	 * Catch double invocations of _begin() which lead to self-deadlock.
@@ -503,8 +507,10 @@ wait:
 	spin_unlock(&policy->transition_lock);
 
 	scale_freq_capacity(policy, freqs);
+#ifdef CONFIG_SMP
 	for_each_cpu(cpu, policy->cpus)
 		trace_cpu_capacity(capacity_curr_of(cpu), cpu);
+#endif
 
 	cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
 }