iommu/amd: Fix pci device refcount leak in ppr_notifier()

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

iommu/amd: Fix pci device refcount leak in ppr_notifier()

As comment of pci_get_domain_bus_and_slot() says, it returns

a pci device with refcount increment, when finish using it,

the caller must decrement the reference count by calling

pci_dev_put(). So call it before returning from ppr_notifier()

to avoid refcount leak.