iommu/amd: Lock dev_data in attach/detach code paths

Make sure that attaching a detaching a device can't race against each
other and protect the iommu_dev_data with a spin_lock in these code
paths.

Fixes: 92d420ec ("iommu/amd: Relax locking in dma_ops path")
Reviewed-by: Filippo Sironi <sironi@amazon.de>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>