ARM: davinci: aintc: wrap davinci_irq_init() with a helper

We're going to extend the davinci_irq_init() function with a config
structure so we can drop the intc-related fields from davinci_soc_info.

Once we do it, we won't be able to use this routine directly as the
init_irq callback. Wrap the calls in additional helpers that don't
take parameters and can be assigned to init_irq.

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