x86/ioapic: Restore IO-APIC irq_chip retrigger callback

commit d32932d0 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: d32932d0  ("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>