ARM: dts: Add Versatile IB2 device tree

The Versatile board can be equipped with a interface board
just named "IB2". This was created in the early 2000s for
prototyping GSM candybar phone form factor products.

The IB2 board contains:
- Cascaded interrupt controller
- Enfora Enabler GSM0308 quad-band module with antenna and
  separate audio jack
- Keypad with joystick
- Sanyo 2.5" color display
- A 28-pin connector for mounting a camera

This adds a DTS file for the combination of the Versatile AB
with an IB2 daughterboard mounted, making the LED blink and
making the system controller available for drivers, such as
the panel driver.

The device tree bindings already exist in
Documentation/devicetree/bindings/arm/arm-boards.

Cc: Mali DP Maintainers <malidp@foss.arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>