refactor afs_CheckServers

refactor afs_CheckServers

basically, we need the ability to reuse this function, so, let's make it work
differently so we can.

Reviewed-on: http://gerrit.openafs.org/3403
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit e8d8a2240a57f9f4a11ee45b60c229d3f8447b86)

Change-Id: I2ad9de15cc5471810abfecf0cbc504da7da624b0
Reviewed-on: http://gerrit.openafs.org/6341
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>