color: Do not set the 'View Details' button for virtual profiles.

Fixes

https://bugzilla.redhat.com/show_bug.cgi?id=1119408

```
Description of problem:
1. Open GNOME Control Center
2. Select 'Color'
3. Select a device (I picked my printer)
4. Select a color profile (I picked Default RGB)
5. Click 'View details'

crash occurred at this point.
```

based on

https://git.gnome.org/browse/gnome-control-center/commit/panels/color/cc-color-panel.c?h=gnome-3-14&id=e9b0527b4b346e2c4ff2ae00bbf0c415186a5a85