remove software_suspend()

Remove software_suspend() and all its users since
pm_suspend(PM_SUSPEND_DISK) should be equivalent and there's no point in
having two interfaces for the same thing.

The patch also changes the valid_state function to return 0 (false) for
PM_SUSPEND_DISK when SOFTWARE_SUSPEND is not configured instead of
accepting it and having the whole thing fail later.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/acpi/sleep/proc.c b/drivers/acpi/sleep/proc.c
index 2d912b7..dcde9dd 100644
--- a/drivers/acpi/sleep/proc.c
+++ b/drivers/acpi/sleep/proc.c
@@ -60,7 +60,7 @@
 	state = simple_strtoul(str, NULL, 0);
 #ifdef CONFIG_SOFTWARE_SUSPEND
 	if (state == 4) {
-		error = software_suspend();
+		error = pm_suspend(PM_SUSPEND_DISK);
 		goto Done;
 	}
 #endif