x86: hibernate: 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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>