x86/ioapic: Restore IO-APIC irq_chip retrigger callback

commit d32932d02e18 removed the irq_retrigger callback from the IO-APIC
chip and did not add it to the new IO-APIC-IR irq chip.

There is no harm because the interrupts are resent in software when the
retrigger callback is NULL, but it's less efficient. So restore them.

[ tglx: Massaged changelog ]

Fixes: d32932d02e18  ("x86/irq: Convert IOAPIC to use hierarchical irqdomain interfaces")
Signed-off-by: Ruslan Ruslichenko <rruslich@cisco.com>
Cc: xe-linux-external@cisco.com
Link: http://lkml.kernel.org/r/1484662432-13580-1-git-send-email-rruslich@cisco.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/apic/io_apic.c

@@ -1875,6 +1875,7 @@ static struct irq_chip ioapic_chip __read_mostly = {
 	.irq_ack		= irq_chip_ack_parent,
 	.irq_eoi		= ioapic_ack_level,
 	.irq_set_affinity	= ioapic_set_affinity,
+	.irq_retrigger		= irq_chip_retrigger_hierarchy,
 	.flags			= IRQCHIP_SKIP_SET_WAKE,
 };
 
@@ -1886,6 +1887,7 @@ static struct irq_chip ioapic_ir_chip __read_mostly = {
 	.irq_ack		= irq_chip_ack_parent,
 	.irq_eoi		= ioapic_ir_ack_level,
 	.irq_set_affinity	= ioapic_set_affinity,
+	.irq_retrigger		= irq_chip_retrigger_hierarchy,
 	.flags			= IRQCHIP_SKIP_SET_WAKE,
 };