arm/dts: OMAP3: Add interrupt-controller bindings for INTC

Update the DTS with the proper information required by the
INTC bindings.

- Add the number of interrupt lines
- Add the reg and the compatible entries.

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