[IA64] xen_domu_defconfig: fix build issues/warnings

- drivers/xen/events.c did not compile
- xen_setup_hook caused a modpost section warning
- the use of u64 (instead of unsigned long long) together with a %llu
  in drivers/xen/balloon.c caused a compiler warning

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/include/asm/idle.h b/arch/ia64/include/asm/idle.h
new file mode 100644
index 0000000..b768501
--- /dev/null
+++ b/arch/ia64/include/asm/idle.h
@@ -0,0 +1,7 @@
+#ifndef _ASM_IA64_IDLE_H
+#define _ASM_IA64_IDLE_H
+
+static inline void enter_idle(void) { }
+static inline void exit_idle(void) { }
+
+#endif /* _ASM_IA64_IDLE_H */