x86, mm: Move after_bootmem to mm_internel.h

it is only used in arch/x86/mm/init*.c

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1353123563-3103-41-git-send-email-yinghai@kernel.org


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>