libadmin: Remove unused error codes

libadmin: Remove unused error codes

A number of functions in the libadmin vos implementation set up
error values, and assign them to 0, but never actually use them
for anything (either further assignment, or returning to the user)
So, just remove these unecessary variables, and make gcc 4.6.0 a
little happier.

Change-Id: Ia4a4a7d8cda855d904f2a84092928f227ea83f3b
Reviewed-on: http://gerrit.openafs.org/4994
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>