butc: Remove dead loop pointer allocations

butc: Remove dead loop pointer allocations

All of these *Ptr values are reset upon each iteration of the
while loop, so we don't need to NULL them immediately before
we go around again.

Caught by clang-analyzer

Change-Id: Iaa5ff6c7b154072e23eae272031919b424568eff
Reviewed-on: http://gerrit.openafs.org/9244
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>