ACPI / PM: Allow device power states to be used for CONFIG_PM unset

Currently, drivers/acpi/device_pm.c depends on CONFIG_PM and all of
the functions defined in there are replaced with static inline stubs
if that option is unset.  However, CONFIG_PM means, roughly, "runtime
PM or suspend/hibernation support" and some of those functions are
useful regardless of that.  For example, they are used by the ACPI
fan driver for controlling fans and acpi_device_set_power() is called
during device removal.  Moreover, device initialization may depend on
setting device power states properly.

For these reasons, make the routines manipulating ACPI device power
states defined in drivers/acpi/device_pm.c available for CONFIG_PM
unset too.

Reported-by: Zhang Rui <rui.zhang@intel.com>
Reported-and-tested-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: 3.9+ <stable@vger.kernel.org>
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index ecb743b..7cad994ee 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -24,7 +24,7 @@
 # Power management related files
 acpi-y				+= wakeup.o
 acpi-y				+= sleep.o
-acpi-$(CONFIG_PM)		+= device_pm.o
+acpi-y				+= device_pm.o
 acpi-$(CONFIG_ACPI_SLEEP)	+= proc.o