Now that XSA-509 went out, here's what actually caused the issue to be
noticed, plus some follow-on cleanup.

1: x86/pass-through: alter locking around pt_irq_{create,destroy}_bind()
2: x86/vPCI: tighten locking assertions
3: x86/pass-through: use simpler locking primitives in pt_irq_{create,destroy}_bind()
4: x86/vPCI: make better use of "pdev" in vpci_msix_arch_print()
5: x86/vMSI: avoid "goto" in msixtbl_pt_unregister()

Jan