cpufreq: Add CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING cpufreq driver flag

The policy->transition_latency field is used for multiple purposes
today and its not straight forward at all. This is how it is used:

A. Set the correct transition_latency value.

B. Set it to CPUFREQ_ETERNAL because:
   1. We don't want automatic dynamic switching (with
      ondemand/conservative) to happen at all.
   2. We don't know the transition latency.

This patch handles the B.1. case in a more readable way. A new flag for
the cpufreq drivers is added to disallow use of cpufreq governors which
have dynamic_switching flag set.

All the current cpufreq drivers which are setting transition_latency
unconditionally to CPUFREQ_ETERNAL are updated to use it. They don't
need to set transition_latency anymore.

There shouldn't be any functional change after this patch.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/cpufreq/unicore2-cpufreq.c b/drivers/cpufreq/unicore2-cpufreq.c
index 6f9dfa8..db62d98 100644
--- a/drivers/cpufreq/unicore2-cpufreq.c
+++ b/drivers/cpufreq/unicore2-cpufreq.c
@@ -58,13 +58,12 @@ static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
 
 	policy->min = policy->cpuinfo.min_freq = 250000;
 	policy->max = policy->cpuinfo.max_freq = 1000000;
-	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 	policy->clk = clk_get(NULL, "MAIN_CLK");
 	return PTR_ERR_OR_ZERO(policy->clk);
 }
 
 static struct cpufreq_driver ucv2_driver = {
-	.flags		= CPUFREQ_STICKY,
+	.flags		= CPUFREQ_STICKY | CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
 	.verify		= ucv2_verify_speed,
 	.target		= ucv2_target,
 	.get		= cpufreq_generic_get,