PM: Introduce struct pm_subsys_data

Introduce struct pm_subsys_data that may be subclassed by subsystems
to store subsystem-specific information related to the device.  Move
the clock management fields accessed through the power.subsys_data
pointer in struct device to the new strucutre.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/include/linux/pm.h b/include/linux/pm.h
index f7c84c9..bf5ee37 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -421,6 +421,13 @@
 
 struct wakeup_source;
 
+struct pm_subsys_data {
+	spinlock_t lock;
+#ifdef CONFIG_PM_CLK
+	struct list_head clock_list;
+#endif
+};
+
 struct dev_pm_info {
 	pm_message_t		power_state;
 	unsigned int		can_wakeup:1;
@@ -462,7 +469,7 @@
 	unsigned long		suspended_jiffies;
 	unsigned long		accounting_timestamp;
 #endif
-	void			*subsys_data;  /* Owned by the subsystem. */
+	struct pm_subsys_data	*subsys_data;  /* Owned by the subsystem. */
 };
 
 extern void update_pm_runtime_accounting(struct device *dev);