volser: allow cloning non-rw volumes

volser: allow cloning non-rw volumes

remove EROFS error which is the only thing preventing a working clone
on a non-RW.

Reviewed-on: http://gerrit.openafs.org/6249
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Alistair Ferguson <alistair.ferguson@mac.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Tested-by: Derrick Brashear <shadow@dementix.org>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit f1de04f3b35e91923efddca57e744b2138619223)

Change-Id: Ieb02a2d2c4d59681f5d6f372c7cd77a181d214dd
Reviewed-on: http://gerrit.openafs.org/6760
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Alistair Ferguson <alistair.ferguson@mac.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>