vol: Log more info on wrong SYNC response length

vol: Log more info on wrong SYNC response length

We log that the length of the response was wrong, so we're dropping
the connection. Log what the actual and expected lengths were, at
least, so we can maybe get a little bit of useful information from
this message.

Change-Id: I499d43c7625712b507698d908feb21477b789563
Reviewed-on: http://gerrit.openafs.org/10829
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>