volume_id: ntfs - fix uuid setting

volume_id: ntfs - fix uuid setting

In my scenario, the ntfs prober did *not* detect the presence of a
ntfs filesystem (i.e. vol_id --probe-all returned *only* ext3).
However, if you examine the source of the ntfs prober, it overwrites
the uuid field of the volume_id object long before it actually
decides there's a valid filesystem there - this resulted in vol_id
returning the rather bizarre combination of type=ext3, but a uuid
populated by the ntfs prober.

https://bugs.edge.launchpad.net/ubuntu/+source/udev/+bug/337015