debian/rules: put init-ceph in /etc/init.d/ceph, not ceph-base

debian/rules: put init-ceph in /etc/init.d/ceph, not ceph-base

When the package name changed from ceph to ceph-base, dh_installinit
started installing the init script into /etc/init.d/ceph-base.  Fix
this by using --name ceph with dh_installinit, which requires
1) naming the .init file ceph-base.ceph.init, and
2) calling dh_installinit separately for each package

Fixes: http://tracker.ceph.com/issues/15329
Signed-off-by: Dan Mick <dan.mick@redhat.com>