sparc64: Fix prototype warnings in hibernate.c

Fix the following warnings:
arch/sparc/power/hibernate.c:22:5: warning: no previous prototype for ‘pfn_is_nosave’
arch/sparc/power/hibernate.c:30:6: warning: no previous prototype for ‘save_processor_state’
arch/sparc/power/hibernate.c:35:6: warning: no previous prototype for ‘restore_processor_state’

The prototypes are available from linux/suspend.h so include that.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Andreas Larsson <[e-mail]>

arch/sparc/power/hibernate.c

···
  * Copyright (C) 2013 Kirill V Tkhai ([e-mail])
  */
 
+#include <linux/suspend.h>
 #include <linux/mm.h>
 
 #include <asm/hibernate.h>