afs: on uuid init fail, don't leave garbage behind

afs: on uuid init fail, don't leave garbage behind

make sure we zero the uuid if we failed

Reviewed-on: http://gerrit.openafs.org/5599
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 9f68e0dd31ddb7bf69ea8ac13b3afe371dd6b7cb)

Change-Id: I20313628c4ac26fc67a2adc909e39bf53742314b
Reviewed-on: http://gerrit.openafs.org/5705
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>