ARM: omap: Don't set iommu pdata da_start and da_end fields

The fields are not used by the driver and will be removed from platform
data. Don't set them.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>