ARM: davinci: aintc: use irq domain

We need to create an irq domain if we want to select SPARSE_IRQ. The
cp-intc driver already supports it, but aintc doesn't. Use the helpers
provided by the generic irq chip abstraction.

Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>