PM / devfreq: Use the available min/max frequency

The commit a76caf55e5b35 ("thermal: Add devfreq cooling") is able
to disable OPP as a cooling device. In result, both update_devfreq()
and {min|max}_freq_show() have to consider the 'opp->available'
status of each OPP.

So, this patch adds the 'scaling_{min|max}_freq' to struct devfreq
in order to indicate the available mininum and maximum frequency
by adjusting OPP interface such as dev_pm_opp_{disable|enable}().
The 'scaling_{min|max}_freq' are used for on both update_devfreq()
and {min|max}_freq_show().

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 597294e..997a9eb 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -120,6 +120,8 @@
  *		touch this.
  * @min_freq:	Limit minimum frequency requested by user (0: none)
  * @max_freq:	Limit maximum frequency requested by user (0: none)
+ * @scaling_min_freq:	Limit minimum frequency requested by OPP interface
+ * @scaling_max_freq:	Limit maximum frequency requested by OPP interface
  * @stop_polling:	 devfreq polling status of a device.
  * @total_trans:	Number of devfreq transitions
  * @trans_table:	Statistics of devfreq transitions
@@ -153,6 +155,8 @@
 
 	unsigned long min_freq;
 	unsigned long max_freq;
+	unsigned long scaling_min_freq;
+	unsigned long scaling_max_freq;
 	bool stop_polling;
 
 	/* information for device frequency transition */