afs: Consolidate ShakeLooseVCaches retry init

Don't duplicate the initialization code in effectively three separate
places. Just goto the top of the loop again.

This should incur no functional change; it's just reorganization.

Reviewed-on: http://gerrit.openafs.org/8848
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit 36959b50e513d4e9d4d2be93965eec2537943de5)

Change-Id: If1277fd4f1cc4adb03695688bcc54ae65715f1a8
Reviewed-on: http://gerrit.openafs.org/8866
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Paul Smeddle <paul.smeddle@gmail.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>