Documentation: dt: gpio-omap: Move interrupt-controller from #interrupt-cells description

The binding documentation for the OMAP GPIO controller has the
"#interrupt-cells" property listed before "#interrupt-controller"
property but its description after.
This is confusing so we move "#interrupt-cells" after the
"interrupt-controller" property so is followed by its description.

While being there, change the properties order to be consistent with
Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
and Documentation/devicetree/bindings/gpio/gpio.txt.

According with these docs, the order of the properties for a gpio-omap
device node should be:

    gpio-controller;
    #gpio-cells = <2>;
    interrupt-controller;
    #interrupt-cells = <2>;

Reported-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Acked-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>