cpufreq: make the "scaling_cur_freq" sysfs entry pollable

Wakeup userspace poll on change of cpu frequency. The userspace
may then take action to change the power/performance
characteristics of the device.

Change-Id: I3030b22084fe7e0143b978a198ddcc579e7d6e83
Signed-off-by: Amar Singhal <asinghal@codeaurora.org>
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index ff15497..36375c05 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -273,8 +273,10 @@
 		trace_cpu_frequency(freqs->new, freqs->cpu);
 		srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
 				CPUFREQ_POSTCHANGE, freqs);
-		if (likely(policy) && likely(policy->cpu == freqs->cpu))
+		if (likely(policy) && likely(policy->cpu == freqs->cpu)) {
 			policy->cur = freqs->new;
+			sysfs_notify(&policy->kobj, NULL, "scaling_cur_freq");
+		}
 		break;
 	}
 }