ACPI: Separate disabling of GPEs from _PTS

The preparation to enter an ACPI system sleep state is now tied to
the disabling of GPEs, but the GPEs should not be disabled before
suspending devices.  Since on ACPI 1.0x systems the _PTS global
control method should be executed before suspending devices, we
need to disable GPEs separately.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Len Brown <len.brown@intel.com>