rtc-cmos / PM: report wakeup event on ACPI RTC alarm

When the ACPI-driven RTC alarm wakes the system, report it as a wakeup
event. This allows userspace to determine that the reason for system
wakeup was RTC alarm.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>