PM: Separate hibernation code from suspend code

[ With Johannes Berg <johannes@sipsolutions.net> ]

Separate the hibernation (aka suspend to disk code) from the other suspend
code.  In particular:

 * Remove the definitions related to hibernation from include/linux/pm.h
 * Introduce struct hibernation_ops and a new hibernate() function to hibernate
   the system, defined in include/linux/suspend.h
 * Separate suspend code in kernel/power/main.c from hibernation-related code
   in kernel/power/disk.c and kernel/power/user.c (with the help of
   hibernation_ops)
 * Switch ACPI (the only user of pm_ops.pm_disk_mode) to hibernation_ops

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 040560d..24d7d78 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -130,16 +130,16 @@
 {
 	int error = 0;
 
-	if (pm_ops && pm_ops->prepare)
-		error = pm_ops->prepare(PM_SUSPEND_DISK);
+	if (hibernation_ops)
+		error = hibernation_ops->prepare();
 
 	return error;
 }
 
 static inline void platform_finish(void)
 {
-	if (pm_ops && pm_ops->finish)
-		pm_ops->finish(PM_SUSPEND_DISK);
+	if (hibernation_ops)
+		hibernation_ops->finish();
 }
 
 static inline int snapshot_suspend(int platform_suspend)
@@ -384,7 +384,7 @@
 		switch (arg) {
 
 		case PMOPS_PREPARE:
-			if (pm_ops && pm_ops->enter) {
+			if (hibernation_ops) {
 				data->platform_suspend = 1;
 				error = 0;
 			} else {
@@ -395,8 +395,7 @@
 		case PMOPS_ENTER:
 			if (data->platform_suspend) {
 				kernel_shutdown_prepare(SYSTEM_SUSPEND_DISK);
-				error = pm_ops->enter(PM_SUSPEND_DISK);
-				error = 0;
+				error = hibernation_ops->enter();
 			}
 			break;