vdagentd: Don't open virtio port if creating uinput fails
vdagentd: Don't open virtio port if creating uinput fails

There is little use in opening the virtio port when uinput creation has failed,
since we will exit as soon as control is returned back to the main loop.

elmarco/vdagent-gtk,elmarco/vdagent-gtk,elmarco/vdagent-gtk