ia64/pv_ops/xen: implement xen pv_irq_ops.

implement xen pv_irq_ops to paravirtualize irq handling
with xen event channel.

Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Akio Takebe <takebe_akio@jp.fujitsu.com>
Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/xen/Makefile

@@ -2,7 +2,7 @@
 # Makefile for Xen components
 #
 
-obj-y := hypercall.o xenivt.o xensetup.o xen_pv_ops.o \
+obj-y := hypercall.o xenivt.o xensetup.o xen_pv_ops.o irq_xen.o \
 	 hypervisor.o xencomm.o xcom_hcall.o grant-table.o
 
 AFLAGS_xenivt.o += -D__IA64_ASM_PARAVIRTUALIZED_XEN