iommu/omap: Remove all module references

The OMAP IOMMU driver has been adapted to the IOMMU framework
for a while now, and it does not support being built as a
module anymore. So, remove all the module references from the
OMAP IOMMU driver.

While at it, also relocate a comment around the subsys_initcall
to avoid a checkpatch strict warning about using a blank line
after function/struct/union/enum declarations.

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