ARM: OMAP2+: Remove legacy device instantiation of IOMMUs

The legacy-style IOMMU device creation is maintained currently only
for OMAP3 SoC, as all other SoCs are DT-boot only, and also to ensure
functionality of the OMAP3 ISP driver, the only in-kernel client user
on OMAP3 that supported both modes.

Commit 78c66fbc ("[media] v4l: omap3isp: Drop platform data support")
removed the legacy device support from the OMAP3 ISP driver, so the
legacy device instantiation of OMAP IOMMU devices is no longer
needed, and is cleaned up.

Signed-off-by: Suman Anna <s-anna@ti.com>
[tony@atomide.com: updated to remove also the Makefile entry]
Signed-off-by: Tony Lindgren <tony@atomide.com>