cpufreq: rename index as driver_data in cpufreq_frequency_table

The "index" field of struct cpufreq_frequency_table was never an
index and isn't used at all by the cpufreq core.  It only is useful
for cpufreq drivers for their internal purposes.

Many people nowadays blindly set it in ascending order with the
assumption that the core will use it, which is a mistake.

Rename it to "driver_data" as that's what its purpose is. All of its
users are updated accordingly.

[rjw: Changelog]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index a3585ea..19fa98e 100644
--- a/Documentation/cpu-freq/cpu-drivers.txt
+++ b/Documentation/cpu-freq/cpu-drivers.txt
@@ -186,7 +186,7 @@
 frequencies, a "frequency table" with some functions might assist in
 some work of the processor driver. Such a "frequency table" consists
 of an array of struct cpufreq_frequency_table entries, with any value in
-"index" you want to use, and the corresponding frequency in
+"driver_data" you want to use, and the corresponding frequency in
 "frequency". At the end of the table, you need to add a
 cpufreq_frequency_table entry with frequency set to CPUFREQ_TABLE_END. And
 if you want to skip one entry in the table, set the frequency to 
@@ -214,10 +214,4 @@
 is the corresponding frequency table helper for the ->target
 stage. Just pass the values to this function, and the unsigned int
 index returns the number of the frequency table entry which contains
-the frequency the CPU shall be set to. PLEASE NOTE: This is not the
-"index" which is in this cpufreq_table_entry.index, but instead
-cpufreq_table[index]. So, the new frequency is
-cpufreq_table[index].frequency, and the value you stored into the
-frequency table "index" field is
-cpufreq_table[index].index.
-
+the frequency the CPU shall be set to.