fs: Remove redundant variable assignments

Remove a number of redundant variable assignments that clang warns
about.

Caught by clang-analyzer

Change-Id: I248e0e3a9f9241084436604532424d6e4b900e31
Reviewed-on: http://gerrit.openafs.org/9194
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>