remove check for disallowing clones of backup or ro volumes

remove check for disallowing clones of backup or ro volumes

removes the if-statement ensuring that the volume being cloned is
not a backup volume, nor a read-only volume. This allows clones
from any type of volume to a given volume. Parent volume meta-data
is maintained, only the cloneId value changes.

Reviewed-on: http://gerrit.openafs.org/5046
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 4e1a65ba7edec519acc67f0dcf2237a0f26e92aa)

Change-Id: Ibda6a8a12804fc35890c99ada6d711e25a50a6c8
Reviewed-on: http://gerrit.openafs.org/5724
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>