ARM: dts: omap3-igep: fix boot fail due wrong compatible match

This patch is based on commit:

016c12d2 ("ARM: OMAP3: Fix hardware detection for omap3630 when booted with device tree")

and fixes a boot hang due the IGEP board being wrongly initialized
as an OMAP3430 platform instead of an OMAP3630.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>