libafs: Always use anonymous VL connections

libafs: Always use anonymous VL connections

afs_NewVolumeByName was using the areq given by the caller for
afs_SetupVolume, which may represent authenticated credentials. Give
afs_SetupVolume &treq instead, which will be anonymous, so we don't
have to deal with rxkad for VL lookups.

Change-Id: Ie990028133173c312d2e5d9de4baa82b99cfdf7d
Reviewed-on: http://gerrit.openafs.org/4666
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>