All IRQs except for IRQ 0 seem to not need acking, so drop acking for them.

The ENMI needs to have the ack done *after* clearing the interrupt source,
otherwise we will get a spurious interrupt for each real interrupt.

So use the new IRQCHIP_EOI_THREADED flag for this in combination with
handle_fasteoi_irq. This uses a separate irq_chip struct for IRQ 0,
since we only want this behavior for IRQ 0.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-sunxi@googlegroups.com
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: http://lkml.kernel.org/r/1394733834-26839-5-git-send-email-hdegoede@redhat.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>