ARM: dts: omap3: Add support for IGEPv2 board

ISEE IGEPv2 is an TI OMAP3 SoC based embedded board.

This patch adds an initial device tree support to boot
an IGEPv2 from the MMC/SD.

Currently is working everything that is supported by DT
on OMAP3 SoCs (MMC/SD, GPIO LEDs, EEPROM, TWL4030 audio).

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Enric Balletbo i Serra <eballetbo@gmail.com>
[benoit.cousson@linaro.org: Update the Makefile for 3.8-rc2]
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>