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 <ulf.hansson@linaro.org>
Acked-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>

include/linux/pm_domain.h

@@ -117,6 +117,7 @@ struct generic_pm_domain_data {
 	struct pm_domain_data base;
 	struct gpd_timing_data td;
 	struct notifier_block nb;
+	void *data;
 };
 
 #ifdef CONFIG_PM_GENERIC_DOMAINS