x86: move e820_mark_nosave_regions to e820.c

and make e820_mark_nosave_regions to take limit_pfn to use max_low_pfn
for 32bit and end_pfn for 64bit

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>