Revert "suspend, xen: enable PM_SLEEP for CONFIG_XEN"

This reverts commit 6fbbec428c8e7bb617da2e8a589af2e97bcf3bc4.

Rafael doesnt like it - it breaks various assumptions.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/power/Kconfig

@@ -82,7 +82,7 @@ config PM_SLEEP_SMP
 
 config PM_SLEEP
 	bool
-	depends on SUSPEND || HIBERNATION || XEN
+	depends on SUSPEND || HIBERNATION
 	default y
 
 config SUSPEND