iommufd/device: Add pasid_attach array to track per-PASID attach

PASIDs of PASID-capable device can be attached to hwpt separately, hence
a pasid array to track per-PASID attachment is necessary. The index
IOMMU_NO_PASID is used by the RID path. Hence drop the igroup->attach.

Link: https://patch.msgid.link/r/20250321171940.7213-10-yi.l.liu@intel.com


Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>