irqchip: davinci-aintc: add a new config structure

Add a config structure that will be used by aintc-based platforms.
It contains the register range resource, number of interrupts and
a list of priorities.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>