x86/power: Fix swsusp_arch_resume prototype

The declaration for swsusp_arch_resume marks it as 'asmlinkage', but the
definition in x86-32 does not, and it fails to include the header with the
declaration. This leads to a warning when building with
link-time-optimizations:

kernel/power/power.h:108:23: error: type of 'swsusp_arch_resume' does not match original declaration [-Werror=lto-type-mismatch]
 extern asmlinkage int swsusp_arch_resume(void);
                       ^
arch/x86/power/hibernate_32.c:148:0: note: 'swsusp_arch_resume' was previously declared here
 int swsusp_arch_resume(void)

This moves the declaration into a globally visible header file and fixes up
both x86 definitions to match it.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Len Brown <len.brown@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: linux-pm@vger.kernel.org
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Link: https://lkml.kernel.org/r/20180202145634.200291-2-arnd@arndb.de

arch/x86/power/hibernate_32.c

@@ -145,7 +145,7 @@ static inline void resume_init_first_level_page_table(pgd_t *pg_dir)
 #endif
 }
 
-int swsusp_arch_resume(void)
+asmlinkage int swsusp_arch_resume(void)
 {
 	int error;
 

arch/x86/power/hibernate_64.c

@@ -174,7 +174,7 @@ static int relocate_restore_code(void)
 	return 0;
 }
 
-int swsusp_arch_resume(void)
+asmlinkage int swsusp_arch_resume(void)
 {
 	int error;
 

include/linux/suspend.h

@@ -384,6 +384,8 @@ extern int swsusp_page_is_forbidden(struct page *);
 extern void swsusp_set_page_free(struct page *);
 extern void swsusp_unset_page_free(struct page *);
 extern unsigned long get_safe_page(gfp_t gfp_mask);
+extern asmlinkage int swsusp_arch_suspend(void);
+extern asmlinkage int swsusp_arch_resume(void);
 
 extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
 extern int hibernate(void);

kernel/power/power.h

@@ -104,9 +104,6 @@ extern int in_suspend;
 extern dev_t swsusp_resume_device;
 extern sector_t swsusp_resume_block;
 
-extern asmlinkage int swsusp_arch_suspend(void);
-extern asmlinkage int swsusp_arch_resume(void);
-
 extern int create_basic_memory_bitmaps(void);
 extern void free_basic_memory_bitmaps(void);
 extern int hibernate_preallocate_memory(void);