pci: Add pci_print()

Cc: Thomas Huth <thuth@redhat.com>
Cc: Andrew Jones <drjones@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Suggested-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Message-Id: <b261e0c3fbfafaa4c38793d4ae632a667f46fb16.1478512824.git.agordeev@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>