ARM: OMAP2/3: intc: Add DT support for TI interrupt controller

Add a function to initialize the OMAP2/3 interrupt controller (INTC)
using a device tree node.

This version take advantage of the new irq_domain_add_legacy API.

Replace some printk() with the proper pr_ macro.

Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>