The current interrupt parsing code was working by accident, because the
default was actually parsing the first node of interrupts.

While that was mostly working (and the flags were actually ignored), this
binding has never been documented, and doesn't work with SoCs that have
multiple interrupt banks anyway.

Add a proper interrupt xlate function, that uses the same description than
the GPIOs (<bank> <pin> <flags>), that will make things less confusing.

The EINT number will still be used as the hwirq number, but won't be
exposed through the DT.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>