PM / core: Drop unused internal inline functions for sysfs

The inline versions of rpm_sysfs_remove() and wakeup_sysfs_add|remove(),
are not being used while CONFIG_PM is unset, hence let's drop them.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>