PM / Domains: Remove pm_genpd_poweron() API

Once genpd could be configured to be built with CONFIG_PM_RUNTIME unset
(nowadays CONFIG_PM), the pm_genpd_poweron() API served a purpose, since
it allowed users to power on a PM domain.

As such configuration no longer is supported, users shall solely rely on
using some of the runtime PM APIs to power on a PM domain.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index dcd451c..8724b47 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -192,6 +192,8 @@
 	queue_work(pm_wq, &genpd->power_off_work);
 }
 
+static int pm_genpd_poweron(struct generic_pm_domain *genpd);
+
 /**
  * __pm_genpd_poweron - Restore power to a given PM domain and its masters.
  * @genpd: PM domain to power up.
@@ -245,7 +247,7 @@
  * pm_genpd_poweron - Restore power to a given PM domain and its masters.
  * @genpd: PM domain to power up.
  */
-int pm_genpd_poweron(struct generic_pm_domain *genpd)
+static int pm_genpd_poweron(struct generic_pm_domain *genpd)
 {
 	int ret;