Increase delay before trying to enable sriov

Starting this too early gets the cards into a bad state. You get the following error when trying to start an mdev device:

```
stderr: 'Error: Parent 0000:81:00.4 is not currently registered for mdev support'
```

Author: jovial

roles/vgpu/templates/nvidia-sriov.service.j2

@@ -13,7 +13,7 @@ User=root
 # NOTE(wszumski): There is a race in the driver initialization where if we run
 # this too early, then the mdev_support_devices entry doesn't show up in sysfs.
 # I was unable to get this to show up again without a reboot.
-ExecStartPre=/bin/sleep 5
+ExecStartPre=/bin/sleep 30
 # NOTE(wszumski): The sriov-manage script will unbind the nvidia driver to
 # initialize the virtual functions.  If it fails part way through, the driver
 # can be left unbound, and subsequent executions of sriov-mange will fail. This