libadmin: Remove redundant memset call

Commit bf78bf2c115659b78c34d3bc9d1934bcff21c8cc added initialisation
of the nbulkentries structure to 0, to avoid freeing garbage due to a
goto fail_... before the structure is initialised. As pointed out by
Andrew Deason, there already is an equivalent memset call later in the
code which is now redundant. Remove it.

Change-Id: I236e6de2a79f4f483be314654225bd52316f5a02
Reviewed-on: http://gerrit.openafs.org/11180
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>