PM / Domains: Document cpuidle-related functions and change their names

The names of the cpuidle-related functions in
drivers/base/power/domain.c are inconsistent with the names of the
other exported functions in that file (the "pm_" prefix is missing
from them) and they are missing kerneldoc comments.

Fix that by adding the missing "pm_" prefix to the names of those
functions and add kerneldoc comments documenting them.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index d9d6083..f2a633a 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -155,8 +155,8 @@
 				  struct gpd_dev_ops *ops,
 				  struct gpd_timing_data *td);
 extern int __pm_genpd_remove_callbacks(struct device *dev, bool clear_td);
-extern int genpd_attach_cpuidle(struct generic_pm_domain *genpd, int state);
-extern int genpd_detach_cpuidle(struct generic_pm_domain *genpd);
+extern int pm_genpd_attach_cpuidle(struct generic_pm_domain *genpd, int state);
+extern int pm_genpd_detach_cpuidle(struct generic_pm_domain *genpd);
 extern void pm_genpd_init(struct generic_pm_domain *genpd,
 			  struct dev_power_governor *gov, bool is_off);
 
@@ -225,11 +225,11 @@
 {
 	return -ENOSYS;
 }
-static inline int genpd_attach_cpuidle(struct generic_pm_domain *genpd, int st)
+static inline int pm_genpd_attach_cpuidle(struct generic_pm_domain *genpd, int st)
 {
 	return -ENOSYS;
 }
-static inline int genpd_detach_cpuidle(struct generic_pm_domain *genpd)
+static inline int pm_genpd_detach_cpuidle(struct generic_pm_domain *genpd)
 {
 	return -ENOSYS;
 }