viced: Correct unblessed attach2 errors

viced: Correct unblessed attach2 errors

Don't set the vp to NULL; instead just go to the general error
handling code. When a volume is not blessed, we just want it to go
offline, not go into an error state. Furthermore, we must free the
volume header when nUsers is set to 0, so manually do so when we do
not call VRequestSalvage_r.

Change-Id: I3ccd61ac219e092a5c9ee52cd563d007bc20a1a1
Reviewed-on: http://gerrit.openafs.org/2476
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>