virtual network devices ignored by udev_resource on powerpc (and possibly other platforms)

an IBM pSeries PowerPC system has a network device that shows in udev:

P: /devices/vio/71000002
E: DEVPATH=/devices/vio/71000002
E: DRIVER=ibmveth
E: MODALIAS=vio:TnetworkSIBM,l-lan
E: OF_COMPATIBLE_0=IBM,l-lan
E: OF_COMPATIBLE_N=1
E: OF_FULLNAME=/vdevice/l-lan@71000002
E: OF_NAME=l-lan
E: OF_TYPE=network
E: SUBSYSTEM=vio

P: /devices/vio/71000002/net/eth0
E: DEVPATH=/devices/vio/71000002/net/eth0
E: ID_NET_NAME_MAC=enx525400004283
E: IFINDEX=2
E: INTERFACE=eth0
E: MATCHDEVID=0x0
E: MATCHIFTYPE=1
E: SUBSYSTEM=net
E: USEC_INITIALIZED=9357

This is a virtual device, and as such, the first device seen here has no PCI vendor or product ID or name. This causes our udev parser to ignore the device. However, it's a perfectly valid eth0 device that needs testing.

The device's environment contains a ID_NET_NAME_MAC variable that in conjunction with bus == "net" should be able to identify this as a valid network interface that needs testing; that should appear as a NETWORK device stanza in udev_resource output.

Here's the udev_resource output on the pSeries:

path: /devices/vio/71000003/host0/target0:0:0/0:0:0:0
bus: scsi
category: DISK
driver: sd
product: QEMU HARDDISK
vendor: QEMU

path: /devices/vio/71000003/host0/target0:0:1/0:0:1:0
bus: scsi
category: DISK
driver: sd
product: QEMU HARDDISK
vendor: QEMU

path: /devices/vio/71000003/host0/target0:0:2/0:0:2:0
bus: scsi
category: CDROM
driver: sr
product: QEMU CD-ROM
vendor: QEMU

There is no NETWORK device, we'd want something like this (cheating because I already have a prototype fix where I got this from):

path: /devices/vio/71000002
bus: net
category: NETWORK
driver: ibmveth
interface: eth0

path: /devices/vio/71000003/host0/target0:0:0/0:0:0:0
bus: scsi
category: DISK
driver: sd
product: QEMU HARDDISK
vendor: QEMU

path: /devices/vio/71000003/host0/target0:0:1/0:0:1:0
bus: scsi
category: DISK
driver: sd
product: QEMU HARDDISK
vendor: QEMU

path: /devices/vio/71000003/host0/target0:0:2/0:0:2:0
bus: scsi
category: CDROM
driver: sr
product: QEMU CD-ROM
vendor: QEMU