fsprobe: call RXAFS_GetTime directly

fsprobe: call RXAFS_GetTime directly

Call RXAFS_GetTime directly instead of using ubik_Call which is
not prototyped and has logic that we don't need/want here since
we're targeting a specific server.

Reviewed-on: http://gerrit.openafs.org/4397
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit ef105dcc4932da804750dea0c922d5814fc5bf15)

Change-Id: If4e430a55d36725f2cf8e5bf04a036062480cfac
Reviewed-on: http://gerrit.openafs.org/6279
Tested-by: Derrick Brashear <shadow@dementix.org>
Reviewed-by: Derrick Brashear <shadow@dementix.org>