New IGEP boards revisions will use another Wifi module, so this patch moves
the DT nodes outside the common omap3-igep.dtsi file to specific DT for every
board.

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>