fix XEN_SAVE_RESTORE Kconfig dependencies

Make XEN_SAVE_RESTORE select HIBERNATE_CALLBACKS.
Remove XEN_SAVE_RESTORE dependency from PM_SLEEP.

Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index 1c7121b..5cc821c 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -39,6 +39,7 @@
 config XEN_SAVE_RESTORE
        bool
        depends on XEN
+       select HIBERNATE_CALLBACKS
        default y
 
 config XEN_DEBUG_FS