pci_set_irq and the other pci irq wrappers use
PCI_INTERRUPT_PIN config register to compute device
INTx pin to assert/deassert.

An irq is allocated using pci_allocate_irq wrapper
only if is needed by non pci devices.

Removed irq related fields from state if not used anymore.
Signed-off-by: NMarcel Apfelbaum <marcel.a@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>