PM / Runtime: Add subsystem data field to struct dev_pm_info

Some subsystems need to attach PM-related data to struct device and
they need to use devres for this purpose.  For their convenience
and to make code more straightforward, add a new field called
subsys_data to struct dev_pm_info and let subsystems use it for
attaching PM-related information to devices.

Convert the ARM shmobile platform to using the new field.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

include/linux/pm.h

@@ -460,6 +460,7 @@ struct dev_pm_info {
 	unsigned long		active_jiffies;
 	unsigned long		suspended_jiffies;
 	unsigned long		accounting_timestamp;
+	void			*subsys_data;  /* Owned by the subsystem. */
 #endif
 };