cpufreq: Fix issue found by coverity in drivers/cpufreq/cpufreq_stats.c

This fixes an issue found in drivers/cpufreq/cpufreq_stats.c by Coverity. Please review as I'm not sure if -EINVAL is the correct value to return at this point.

Error reported:
CID: 2642
Checker: NULL_RETURNS (help)
File: /export2/p4-coverity/mc2/linux26/drivers/cpufreq/cpufreq_stats.c
Function: cpufreq_stats_create_table
Description: Dereferencing NULL value "data"

Patch description:
The return of cpufreq_cpu_get can be NULL, check return code and return -EINVAL if it is NULL.

---

 cpufreq_stats.c |    6 ++++++
 1 files changed, 6 insertions(+)

@@ -197,6 +197,11 @@
 	memset(stat, 0, sizeof (struct cpufreq_stats));
 
 	data = cpufreq_cpu_get(cpu);
+	if (data == NULL) {
+		ret = -EINVAL;
+		goto error_get_fail;
+	}
+
 	if ((ret = sysfs_create_group(&data->kobj, &stats_attr_group)))
 		goto error_out;
 

@@ -244,6 +249,7 @@
 	return 0;
 error_out:
 	cpufreq_cpu_put(data);
+error_get_fail:
 	kfree(stat);
 	cpufreq_stats_table[cpu] = NULL;
 	return ret;

Yep, EINVAL is fine. I checked this into the cpufreq-git tree (though I did it by hand as it's changed there recently
-- working against the -mm tree would save you this hassle in future btw).

Thanks

Dave