PM / hibernate: Correct documentation

Correct the meaning of PM_HIBERNATION_PREPARE in the docs.

References: http://lkml.kernel.org/r/20130512162717.GA6305@pd.tnic
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/Documentation/power/notifiers.txt b/Documentation/power/notifiers.txt
index c2a4a34..a81fa25 100644
--- a/Documentation/power/notifiers.txt
+++ b/Documentation/power/notifiers.txt
@@ -15,8 +15,10 @@
 The subsystems or drivers having such needs can register suspend notifiers that
 will be called upon the following events by the PM core:
 
-PM_HIBERNATION_PREPARE	The system is going to hibernate or suspend, tasks will
-			be frozen immediately.
+PM_HIBERNATION_PREPARE	The system is going to hibernate, tasks will be frozen
+			immediately. This is different from PM_SUSPEND_PREPARE
+			below because here we do additional work between notifiers
+			and drivers freezing.
 
 PM_POST_HIBERNATION	The system memory state has been restored from a
 			hibernation image or an error occurred during