x86, hibernate: Extract the common code of 64/32 bit system

Reduce the hibernation code duplication between x86-32 and x86-64
by extracting the common code into hibernate.c.

Currently only pfn_is_nosave() is the activated common
function in hibernate.c

No functional change.

Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Zhimin Gu <kookoo.gu@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>