[IA64] Changed from page to page_info

[IA64] Changed from page to page_info

This patch changed from "struct page" to "struct page_info" in the below files.
 - xen/arch/ia64/xen/domain.c
 - xen/arch/ia64/xen/mm_init.c
 - xen/arch/ia64/xen/xenmem.c
 - xen/arch/ia64/xen/xenmisc.c
 - xen/include/asm-ia64/config.h
 - xen/include/asm-ia64/mm.h

This patch is "step1" which we showed by the following mail.
http://lists.xensource.com/archives/html/xen-ia64-devel/2006-03/msg00305.html

Signed-off-by: Akio Takebe <takebe_akio@jp.fujitsu.com>
Signed-off-by: Masaki Kanno <kanno.masaki@jp.fujitsu.com>