PM: Convert PM notifiers to out-of-line code

This patch (as1008b) converts the PM notifier routines from inline
calls to out-of-line code.  It also prevents pm_chain_head from
being created when CONFIG_PM_SLEEP isn't enabled, and EXPORTs the
notifier registration and unregistration routines.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/kernel/power/power.h b/kernel/power/power.h
index f9f0d4d..a9732fd 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -172,14 +172,10 @@
 }
 #endif /* !CONFIG_SUSPEND */
 
-/* kernel/power/common.c */
-extern struct blocking_notifier_head pm_chain_head;
-
-static inline int pm_notifier_call_chain(unsigned long val)
-{
-	return (blocking_notifier_call_chain(&pm_chain_head, val, NULL)
-			== NOTIFY_BAD) ? -EINVAL : 0;
-}
+#ifdef CONFIG_PM_SLEEP
+/* kernel/power/main.c */
+extern int pm_notifier_call_chain(unsigned long val);
+#endif
 
 #ifdef CONFIG_HIGHMEM
 unsigned int count_highmem_pages(void);