ia64/xen: compilation fix

ia64/xen: compilation fix

This patch fixes the following compilation error introduced by a PCI related
features.

The change set of 5dd1af9f84c79bedd589db89e71ca733f3bf0ebd moves some
xen related definitions from the arch header file
(x86/include/asm/xen/hypervisor.h) to the common header file
(include/xen/xen.h).  So ia64/xen also follows it.

In file included from linux-next/include/xen/grant_table.h:41,
                 from linux-next/drivers/block/xen-blkfront.c:48:
linux-next/arch/ia64/include/asm/xen/hypervisor.h:43: error: nested redefinition of 'enum xen_domain_type'
linux-next/arch/ia64/include/asm/xen/hypervisor.h:43: error: redeclaration of 'enum xen_domain_type'
linux-next/arch/ia64/include/asm/xen/hypervisor.h:44: error: redeclaration of enumerator 'XEN_NATIVE'
linux-next/include/xen/xen.h:5: error: previous definition of 'XEN_NATIVE' was here
linux-next/arch/ia64/include/asm/xen/hypervisor.h:45: error: redeclaration of enumerator 'XEN_PV_DOMAIN'
linux-next/include/xen/xen.h:6: error: previous definition of 'XEN_PV_DOMAIN' was here
linux-next/arch/ia64/include/asm/xen/hypervisor.h:46: error: redeclaration of enumerator 'XEN_HVM_DOMAIN'
linux-next/include/xen/xen.h:7: error: previous definition of 'XEN_HVM_DOMAIN' was here

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>