PM: hibernate: Add __init annotation to swsusp_header_init()

'swsusp_header_init()' is only called via 'core_initcall'.
It can be marked as __init to save a few bytes of memory.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

kernel/power/swap.c

@@ -1590,7 +1590,7 @@ int swsusp_unmark(void)
 }
 #endif
 
-static int swsusp_header_init(void)
+static int __init swsusp_header_init(void)
 {
 	swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
 	if (!swsusp_header)