ukernel: output dataversion in stat struct if possible

ukernel: output dataversion in stat struct if possible

we already have this data; if we can output it, do so.

Reviewed-on: http://gerrit.openafs.org/5510
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 955bab670d0aed714fc940b5be7e2b75896a63d0)

Change-Id: I9ce28fcb20cee8f15f71cd734b9da0ad85c12c3f
Reviewed-on: http://gerrit.openafs.org/5541
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>