iommu/omap: Remove ver debugfs entry

The debugfs entry 'ver' to read the OMAP IOMMU version is
not much useful for developers, so it has been removed. The
same can be deduced from the register dump, provided by the
debugfs entry 'regs', REVISION register. This also allows us
to remove the omap_iommu_arch_revision() which is currently
returning a fixed value.

Signed-off-by: Suman Anna <s-anna@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>