"-set device" doesn't work with device specified in json
Description of problem:
The above QEMU command line results in:
```
qemu-system-x86_64: -set device.ua-igd.x-igd-gms=1: there is no device "ua-igd" defined
```
While the following command works:
```
qemu-system-x86_64 -accel kvm -m 8192 -nodefaults -display none -net none -device vfio-pci,host=0000:00:02.0,id=ua-igd -set device.ua-igd.x-igd-gms=1
```
libvirt has moved to the json device specification, therefore I can no longer associate use a <qemu:commandline> section to set driver options for a specific device with this broken id association.
Steps to reproduce:
1. Create a device with an ID and use -set device.$ID to set a driver option for the device
2. Note failure when using json device format vs legacy device specification
3. Profit
Additional information: