fsprobe: Get rid of unused hostname buffer

When we copy the user supplied hostname into the fixed length
hnamebuf array, we might overflow it. As we never use this buffer,
just get rid of it.

Caught by coverity (#985913)

Change-Id: I4cda6279cd667343856deeb425dceaf00f7904b6
Reviewed-on: http://gerrit.openafs.org/9394
Reviewed-by: Marc Dionne <marc.c.dionne@gmail.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>