iommu/vt-d: Remove unused dma map/unmap trace events

With commit c588072b ("iommu/vt-d: Convert intel iommu driver to
the iommu ops"), the trace events for dma map/unmap have no users any
more. Cleanup them to make the code neat.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210323010600.678627-2-baolu.lu@linux.intel.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>