iommu: Statically set module owner

It happens that the 3 drivers which first supported being modular are
also ones which play games with their pgsize_bitmap, so have non-const
iommu_ops where dynamically setting the owner manages to work out OK.
However, it's less than ideal to force that upon all drivers which want
to be modular - like the new sprd-iommu driver which now has a potential
bug in that regard - so let's just statically set the module owner and
let ops remain const wherever possible.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/31423b99ff609c3d4b291c701a7a7a810d9ce8dc.1617285386.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>