iommu/fsl: Various cleanups

Currently a PAMU driver patch is very likely to receive some
checkpatch complaints about the code in the context of the
patch. This patch is an attempt to fix most of that and make
the driver more readable

Also fixed a subset of the sparse and coccinelle reported
issues.

Signed-off-by: Emil Medve <Emilian.Medve@Freescale.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>