omap_intc: Qdevify

Convert the omap_intc devices to qdev. This includes adding
a 'revision' property which will be needed for omap3.

The bulk of this patch is the replacement of "s->irq[x][y]"
with  "qdev_get_gpio_in(s->ih[x], y)" now that the interrupt
controller exposes its input lines as qdev gpio inputs.

The devices are named "omap-intc" and "omap2-intc", following
the filename and the OMAP2/3 hardware names, although some
internal functions are still named "omap_inth_*".

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
