x86/vioapic: issue EOI to dpci when switching pin to edge trigger mode

x86/vioapic: issue EOI to dpci when switching pin to edge trigger mode

When an IO-APIC pin is switched from level to edge trigger mode the
IRR bit is cleared, so it can be used as a way to EOI an interrupt at
the IO-APIC level.

Such EOI however does not get forwarded to the dpci code like it's
done for the local APIC initiated EOI. This change adds the code in
order to notify dpci of such EOI, so that dpci and the interrupt
controller are in sync.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>