[IA64] Stop using the deprecated __do_IRQ() code path

Thomas Gleixner <tglx@linutronix.de> wrote:
>__do_IRQ() has been deprecated after a two years migration phase in
>commit 0e57aa1. Since then another 18 months have gone by ...

Mostly trivial stuff for this. The only tricky part was realizing
that the new handler_*_irq() paths do not use desc->chip->end(irq).
Not a problem for the edge case as the ia64 iosapic routine for
that was nop(). But the "level" case handled interrupt migration
there.  Just use a slightly modified version of the "end" routine
as "unmask" for the level triggered case.

Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/irq_ia64.c

@@ -635,6 +635,7 @@ ia64_native_register_percpu_irq (ia64_vector vec, struct irqaction *action)
 	desc->chip = &irq_type_ia64_lsapic;
 	if (action)
 		setup_irq(irq, action);
+	set_irq_handler(irq, handle_percpu_irq);
 }
 
 void __init