debian/control: ceph-common (>> 0.94.2) must be >= 0.94.2-2

debian/control: ceph-common (>> 0.94.2) must be >= 0.94.2-2

The d8733be2ef8874b9a858a7ffddfb81b9b656e9a6 backport introduced a
regression by adding an incorrect Depends / Break combo supposed to
reflect the fact that ceph_argparse moved from ceph to ceph-common after
v0.94.2. It assumed the package is released under the 0.94.2 version
where in reality it is released under the 0.94.2-1xxx version (where xxx
is trusty, jessie etc.).

The Depends / Break combo is changed to use 0.94.2-2 instead.

See also http://tracker.ceph.com/issues/12529 for a larger discussion.

http://tracker.ceph.com/issues/11998 Fixes: #11998

Signed-off-by: Loic Dachary <ldachary@redhat.com>