PM: Make *_DEV_PM_OPS macros use __maybe_unused

This way, when the dev_pm_ops instance is not referenced anywhere, it
will simply be dropped by the compiler without a warning.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: pcercuei

include/linux/pm.h

@@ -351,7 +351,7 @@ struct dev_pm_ops {
  * to RAM and hibernation.
  */
 #define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
-const struct dev_pm_ops name = { \
+const struct dev_pm_ops __maybe_unused name = { \
 	SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
 }
 
@@ -369,7 +369,7 @@ const struct dev_pm_ops name = { \
  * .runtime_resume(), respectively (and analogously for hibernation).
  */
 #define UNIVERSAL_DEV_PM_OPS(name, suspend_fn, resume_fn, idle_fn) \
-const struct dev_pm_ops name = { \
+const struct dev_pm_ops __maybe_unused name = { \
 	SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
 	SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
 }