PM: hibernate: powerpc: Expose pfn_is_nosave() prototype

The declaration for pfn_is_nosave is only available in
kernel/power/power.h. Since this function can be override in arch,
expose it globally. Having a prototype will make sure to avoid warning
(sometime treated as error with W=1) such as:

  arch/powerpc/kernel/suspend.c:18:5: error: no previous prototype for 'pfn_is_nosave' [-Werror=missing-prototypes]

This moves the declaration into a globally visible header file and add
missing include to avoid a warning on powerpc.

Also remove the duplicated prototypes since not required anymore.

Signed-off-by: Mathieu Malaterre <malat@debian.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

arch/powerpc/kernel/suspend.c

@@ -7,6 +7,7 @@
  */
 
 #include <linux/mm.h>
+#include <linux/suspend.h>
 #include <asm/page.h>
 #include <asm/sections.h>
 

arch/s390/kernel/entry.h

@@ -63,7 +63,6 @@ void __init startup_init(void);
 void die(struct pt_regs *regs, const char *str);
 int setup_profiling_timer(unsigned int multiplier);
 void __init time_init(void);
-int pfn_is_nosave(unsigned long);
 void s390_early_resume(void);
 unsigned long prepare_ftrace_return(unsigned long parent, unsigned long sp, unsigned long ip);
 

include/linux/suspend.h

@@ -426,6 +426,7 @@ extern bool system_entering_hibernation(void);
 extern bool hibernation_available(void);
 asmlinkage int swsusp_save(void);
 extern struct pbe *restore_pblist;
+int pfn_is_nosave(unsigned long pfn);
 #else /* CONFIG_HIBERNATION */
 static inline void register_nosave_region(unsigned long b, unsigned long e) {}
 static inline void register_nosave_region_late(unsigned long b, unsigned long e) {}

kernel/power/power.h

@@ -75,8 +75,6 @@ static inline void hibernate_reserved_size_init(void) {}
 static inline void hibernate_image_size_init(void) {}
 #endif /* !CONFIG_HIBERNATION */
 
-extern int pfn_is_nosave(unsigned long);
-
 #define power_attr(_name) \
 static struct kobj_attribute _name##_attr = {	\
 	.attr	= {				\