irqchip: atmel-aic: Fix irqdomain initialization

First of all IRQCHIP_SKIP_SET_WAKE is not a valid irq_gc_flags and thus
should not be passed as the last argument of
irq_alloc_domain_generic_chips.

Then pass the correct handler (handle_fasteoi_irq) to
irq_alloc_domain_generic_chips instead of manually re-setting it in the
initialization loop.

And eventually initialize default irq flags to the pseudo standard:
IRQ_REQUEST | IRQ_PROBE | IRQ_AUTOEN.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Kevin Hilman <khilman@linaro.org>
Fixes: b1479ebb

 ("irqchip: atmel-aic: Add atmel AIC/AIC5 drivers")
Cc: <stable@vger.kernel.org> # v3.17+
Link: https://lkml.kernel.org/r/1415712816-9202-1-git-send-email-boris.brezillon@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>