CVE-2026-89451: iommu/sva: Set handle->dev before the SVA handle is visible

In the Linux kernel, the following vulnerability has been resolved: iommu/sva: Set handle->dev before the SVA handle is visible iommu_attach_device_pasid() installs the new SVA attach handle in the group PASID lookup before iommu_sva_bind_device() returns. A concurrent bind can therefore find and reuse the same handle after iommu_sva_lock is dropped. handle->dev was initialized after dropping iommu_sva_lock. This leaves a window where a racing bind can return a handle whose dev pointer is still NULL. A subsequent iommu_sva_unbind_device() can then dereference it via handle->dev->iommu_group. Initialize handle->dev before releasing iommu_sva_lock so any visible SVA handle is fully initialized.