libadmin: remove duplicate dependency

afs_AdminPtsErrors.h was listed twice in the dependency
afs_utilAdmin.o dependency list.

Change-Id: I4bf37d0502e26e05f912a136045814e32de73c4a
Reviewed-on: http://gerrit.openafs.org/10725
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Marc Dionne <marc.c.dionne@gmail.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>