Remove reference from mkcephfs.

A bit of colission from spec changes for the rhel7/ceph-common
changes and alfredo's pull request for wip-die-ceph-mkcephfs.

Signed-off-by: Sandon Van Ness <sandon@inktank.com>
(cherry picked from commit 1526546ddcfd4230403d0d2364575c4e46970f8d)