ARM: OMAP2+: Make some definitions local

Move some of the definitions in omap-iommu.h that can be made local to
either drivers/iommu.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Omar Ramirez Luna <omar.luna@linaro.org>
Signed-off-by: Ido Yariv <ido@wizery.com>
Acked-by: Ohad Ben-Cohen <ohad@wizery.com>
Acked-by: Joerg Roedel <joro@8bytes.org>
[tony@atomide.com: updated for header changes in the series]
Signed-off-by: Tony Lindgren <tony@atomide.com>