Start using the generic fault report mechanism, as provided by
the IOMMU core, and remove its now-redundant omap_iommu_set_isr API.

Currently we're only interested in letting upper layers know about the
fault, so in case the faulting device is a remote processor, they could
restart it.

Dynamic PTE/TLB loading is not supported.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>