ARM: OMAP2+: Remove module references from IOMMU machine layer

The OMAP IOMMU driver has been adapted to the IOMMU framework
for a while now, and it no longer supports being built as a
module. Cleanup all the module related references both from
the code and in the build.

While at it, also relocate a comment around the 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>
Signed-off-by: Tony Lindgren <tony@atomide.com>