iommu: Change iommu driver to call attach_device_to_domain trace event

Change iommu driver to call attach_device_to_domain trace event. This
iommu_device class event can be enabled to trigger when devices are attached
to a domain. Trace information includes device name.

Testing:
Added trace calls to iommu_prepare_identity_map() for testing some of the
conditions that are hard to trigger. Here is the trace from the testing:

      swapper/0-1     [003] ....     1.854102: attach_device_to_domain: IOMMU: device=0000:00:02.0

Signed-off-by: Shuah Khan <shuah.kh@samsung.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>