ubik: Convert DoProbe 'i' to 'nconns'

DoProbe was using the variable 'i' to keep track of how many
connections we have in the conns array. Keep track of this separately
using a variable called 'nconns' instead, to make this function a bit
less confusing.

Change-Id: Ica2b4901c083b315e901366820042fad64030b3c
Reviewed-on: http://gerrit.openafs.org/11540
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>