PM / Domains: Add generic data pointer to genpd data struct

Add a void *data pointer to struct generic_pm_domain_data. Because this
exists for each device associated with a genpd it will allow us to
assign per-device data if needed on a platform for control of that
specific device.

Acked-by: Ulf Hansson <[e-mail]>
Acked-by: Kevin Hilman <[e-mail]>
Signed-off-by: Dave Gerlach <[e-mail]>
Signed-off-by: Santosh Shilimkar <[e-mail]>

include/linux/pm_domain.h

···
 	struct pm_domain_data base;
 	struct gpd_timing_data td;
 	struct notifier_block nb;
+	void *data;
 };
 
 #ifdef CONFIG_PM_GENERIC_DOMAINS