iommu: Fix NULL group->domain dereference in pci_dev_reset_iommu_done()

In the Linux kernel, the following vulnerability has been resolved:

iommu: Fix NULL group->domain dereference in pci_dev_reset_iommu_done()

Local sashiko review pointed it out that group->domain could be NULL when

a default domain fails to allocate during the first probe, which can crash

at domain->ops->attach_dev dereference in __iommu_attach_device() invoked

by pci_dev_reset_iommu_done().

pci_dev_reset_iommu_prepare() is fine as an old_domain pointer can be NULL.

Skip the re-attach in pci_dev_reset_iommu_done() to fix the bug.