ACPI / PM: Move routines for adding/removing device wakeup notifiers

ACPI routines for adding and removing device wakeup notifiers are
currently defined in a PCI-specific file, but they will be necessary
for non-PCI devices too, so move them to a separate file under
drivers/acpi and rename them to indicate their ACPI origins.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 82422fe..a2711fa 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -21,9 +21,10 @@
 acpi-y				+= osl.o utils.o reboot.o
 acpi-y				+= nvs.o
 
-# sleep related files
+# Power management related files
 acpi-y				+= wakeup.o
 acpi-y				+= sleep.o
+acpi-$(CONFIG_PM)		+= device_pm.o
 acpi-$(CONFIG_ACPI_SLEEP)	+= proc.o