ARM: dts: omap3-igep00x0: Move NAND configuration to a common place.

At this moment all supported boards use same NAND chip, so has more sense
move the GPMC and NAND configuration to the omap3-igep.dtsi common place.

Signed-off-by: Enric Balletbo i Serra <eballetbo@iseebcn.com>
Acked-by: Javier Martinez Canillas <javier@dowhile0.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>