cpufreq: Introduce macros for cpufreq_frequency_table iteration

Many cpufreq drivers need to iterate over the cpufreq_frequency_table
for various tasks.

This patch introduces two macros which can be used for iteration over
cpufreq_frequency_table keeping a common coding style across drivers:

- cpufreq_for_each_entry: iterate over each entry of the table
- cpufreq_for_each_valid_entry: iterate over each entry that contains
a valid frequency.

It should have no functional changes.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/linux/cpufreq.h

@@ -468,6 +468,27 @@ struct cpufreq_frequency_table {
 				    * order */
 };
 
+bool cpufreq_next_valid(struct cpufreq_frequency_table **pos);
+
+/*
+ * cpufreq_for_each_entry -	iterate over a cpufreq_frequency_table
+ * @pos:	the cpufreq_frequency_table * to use as a loop cursor.
+ * @table:	the cpufreq_frequency_table * to iterate over.
+ */
+
+#define cpufreq_for_each_entry(pos, table)	\
+	for (pos = table; pos->frequency != CPUFREQ_TABLE_END; pos++)
+
+/*
+ * cpufreq_for_each_valid_entry -     iterate over a cpufreq_frequency_table
+ *	excluding CPUFREQ_ENTRY_INVALID frequencies.
+ * @pos:        the cpufreq_frequency_table * to use as a loop cursor.
+ * @table:      the cpufreq_frequency_table * to iterate over.
+ */
+
+#define cpufreq_for_each_valid_entry(pos, table)	\
+	for (pos = table; cpufreq_next_valid(&pos); pos++)
+
 int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
 				    struct cpufreq_frequency_table *table);