Add new GPE public interface - AcpiMarkGpeForWake.

Some potential callers of AcpiSetupGpeForWake may know in advance that
there won't be any notify handlers installed for device wake notifications
from the given GPE (one example is a button GPE in Linux). For these cases,
AcpiMarkGpeForWake should be used instead of AcpiSetupGpeForWake.
This will set the ACPI_GPE_CAN_WAKE flag for the GPE without trying to
setup implicit wake notification for it (since there's no handler method).
Rafael Wysocki.