iommu/amd: xarray to track protection_domain->iommu list

Use xarray to track IOMMU attached to protection domain instead of
static array of MAX_IOMMUS. Also add lockdep assertion.

Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20241030063556.6104-5-vasant.hegde@amd.com


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