ARM: dts: omap3-igep0030: add mux conf for GPIO LED

The IGEP COM MOdule has a GPIO LED connected to OMAP
pins. Configure this pin as output GPIO.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Enric Balletbo i Serra <eballetbo@iseebcn.com>
Signed-off-by: Benoit Cousson <bcousson@baylibre.com>