iommu: Change iommu driver to call remove_device_to_group trace event
Change iommu driver to call remove_device_to_group trace event. This
iommu_group class event can be enabled to trigger when devices get
removed from an iommu group. Trace information includes iommu group id and
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: