cpufreq: ondemand:kernel NULL pointer dereference at dbs_check_cpu

Function dbs_check_cpu  calls __cpufreq_driver_getavg
With  policy as IN/OUT parameter.
There is possiblity of policy becoming NULL in
 __cpufreq_driver_getavg. Same policy is getting
accessed in the for loop which leads to NULL pointer dereference.
So NULL check is required for the policy

CRs-fixed: 582925
Change-Id: Ib8d8de8d66500430a5aa4c275937640e4f934aa8
Signed-off-by: Swetha Chikkaboraiah <schikk@codeaurora.org>

drivers/cpufreq/cpufreq_ondemand.c

@@ -767,6 +767,8 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 
 	this_dbs_info->freq_lo = 0;
 	policy = this_dbs_info->cur_policy;
+	if(policy == NULL)
+		return;
 
 	/*
 	 * Every sampling_rate, we check, if current idle time is less
@@ -841,6 +843,8 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 		j_dbs_info->max_load  = max(cur_load, j_dbs_info->prev_load);
 		j_dbs_info->prev_load = cur_load;
 		freq_avg = __cpufreq_driver_getavg(policy, j);
+		if (policy == NULL)
+			return;
 		if (freq_avg <= 0)
 			freq_avg = policy->cur;